diff --git a/src/Flurl.Http/Configuration/FlurlClientBuilder.cs b/src/Flurl.Http/Configuration/FlurlClientBuilder.cs
index 8c05ed54..aaced9ea 100644
--- a/src/Flurl.Http/Configuration/FlurlClientBuilder.cs
+++ b/src/Flurl.Http/Configuration/FlurlClientBuilder.cs
@@ -3,19 +3,15 @@
 using System.Linq;
 using System.Net.Http;
 using System.Runtime.Versioning;
+using Flurl.Util;
 
 namespace Flurl.Http.Configuration
 {
 	/// <summary>
 	/// A builder for configuring IFlurlClient instances.
 	/// </summary>
-	public interface IFlurlClientBuilder
+	public interface IFlurlClientBuilder : ISettingsContainer, IHeadersContainer
 	{
-		/// <summary>
-		/// Configure the IFlurlClient's Settings.
-		/// </summary>
-		IFlurlClientBuilder WithSettings(Action<FlurlHttpSettings> configure);
-
 		/// <summary>
 		/// Configure the HttpClient wrapped by this IFlurlClient.
 		/// </summary>
@@ -57,10 +53,15 @@ public class FlurlClientBuilder : IFlurlClientBuilder
 
 		private readonly string _baseUrl;
 		private readonly List<Func<DelegatingHandler>> _addMiddleware = new();
-		private readonly List<Action<FlurlHttpSettings>> _settingsConfigs = new();
 		private readonly List<Action<HttpClient>> _clientConfigs = new();
 		private readonly List<Action<HttpMessageHandler>> _handlerConfigs = new();
 
+		/// <inheritdoc />
+		public FlurlHttpSettings Settings { get; } = new();
+
+		/// <inheritdoc />
+		public INameValueList<string> Headers { get; } = new NameValueList<string>(false); // header names are case-insensitive https://stackoverflow.com/a/5259004/62600
+
 		/// <summary>
 		/// Creates a new FlurlClientBuilder.
 		/// </summary>
@@ -68,12 +69,6 @@ public FlurlClientBuilder(string baseUrl = null) {
 			_baseUrl = baseUrl;
 		}
 
-		/// <inheritdoc />
-		public IFlurlClientBuilder WithSettings(Action<FlurlHttpSettings> configure) {
-			_settingsConfigs.Add(configure);
-			return this;
-		}
-
 		/// <inheritdoc />
 		public IFlurlClientBuilder AddMiddleware(Func<DelegatingHandler> create) {
 			_addMiddleware.Add(create);
@@ -128,11 +123,7 @@ public IFlurlClient Build() {
 			foreach (var config in _clientConfigs)
 				config(httpCli);
 
-			var flurlCli = new FlurlClient(httpCli, _baseUrl);
-			foreach (var config in _settingsConfigs)
-				config(flurlCli.Settings);
-
-			return flurlCli;
+			return new FlurlClient(httpCli, _baseUrl, Settings, Headers);
 		}
 	}
 }
diff --git a/src/Flurl.Http/FlurlClient.cs b/src/Flurl.Http/FlurlClient.cs
index d2b2843f..89e56e83 100644
--- a/src/Flurl.Http/FlurlClient.cs
+++ b/src/Flurl.Http/FlurlClient.cs
@@ -12,7 +12,7 @@ namespace Flurl.Http
 	/// <summary>
 	/// Interface defining FlurlClient's contract (useful for mocking and DI)
 	/// </summary>
-	public interface IFlurlClient : IHttpSettingsContainer, IDisposable {
+	public interface IFlurlClient : ISettingsContainer, IHeadersContainer, IDisposable {
 		/// <summary>
 		/// Gets the HttpClient that this IFlurlClient wraps.
 		/// </summary>
@@ -67,26 +67,32 @@ public FlurlClient(string baseUrl = null) : this(_defaultFactory.Value.CreateHtt
 		/// Flurl's re-implementation of those features may not work properly.
 		/// </summary>
 		/// <param name="httpClient">The instantiated HttpClient instance.</param>
-		/// <param name="baseUrl">The base URL associated with this client.</param>
-		public FlurlClient(HttpClient httpClient, string baseUrl = null) {
+		/// <param name="baseUrl">Optional. The base URL associated with this client.</param>
+		/// <param name="settings">Optional. A pre-initialized collection of settings.</param>
+		/// <param name="headers">Optional. A pre-initialized collection of default request headers.</param>
+		public FlurlClient(HttpClient httpClient, string baseUrl = null, FlurlHttpSettings settings = null, INameValueList<string> headers = null) {
 			HttpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
 			BaseUrl = baseUrl ?? httpClient.BaseAddress?.ToString();
-			foreach (var header in httpClient.DefaultRequestHeaders.SelectMany(h => h.Value, (kv, v) => (kv.Key, v)))
-				Headers.Add(header);
 
-			Settings.Timeout = httpClient.Timeout;
+			Settings = settings ?? new FlurlHttpSettings { Timeout = httpClient.Timeout };
 			// Timeout can be overridden per request, so don't constrain it by the underlying HttpClient
 			httpClient.Timeout = Timeout.InfiniteTimeSpan;
+
+			Headers = headers ?? new NameValueList<string>(false); // header names are case-insensitive https://stackoverflow.com/a/5259004/62600
+			foreach (var header in httpClient.DefaultRequestHeaders.SelectMany(h => h.Value, (kv, v) => (kv.Key, v))) {
+				if (!Headers.Contains(header.Key))
+					Headers.Add(header);
+			}
 		}
 
 		/// <inheritdoc />
 		public string BaseUrl { get; set; }
 
 		/// <inheritdoc />
-		public FlurlHttpSettings Settings { get; } = new();
+		public FlurlHttpSettings Settings { get; }
 
 		/// <inheritdoc />
-		public INameValueList<string> Headers { get; } = new NameValueList<string>(false); // header names are case-insensitive https://stackoverflow.com/a/5259004/62600
+		public INameValueList<string> Headers { get; }
 
 		/// <inheritdoc />
 		public HttpClient HttpClient { get; }
@@ -153,10 +159,7 @@ public async Task<IFlurlResponse> SendAsync(IFlurlRequest request, HttpCompletio
 
 		private void SyncHeaders(IFlurlRequest req, HttpRequestMessage reqMsg) {
 			// copy any client-level (default) headers to FlurlRequest
-			foreach (var header in this.Headers.ToList()) {
-				if (!req.Headers.Contains(header.Name))
-					req.Headers.Add(header.Name, header.Value);
-			}
+			FlurlRequest.SyncHeaders(this, req);
 
 			// copy headers from FlurlRequest to HttpRequestMessage
 			foreach (var header in req.Headers)
diff --git a/src/Flurl.Http/FlurlRequest.cs b/src/Flurl.Http/FlurlRequest.cs
index 6d52f2e1..ce11b73a 100644
--- a/src/Flurl.Http/FlurlRequest.cs
+++ b/src/Flurl.Http/FlurlRequest.cs
@@ -13,7 +13,7 @@ namespace Flurl.Http
 	/// Represents an HTTP request. Can be created explicitly via new FlurlRequest(), fluently via Url.Request(),
 	/// or implicitly when a call is made via methods like Url.GetAsync().
 	/// </summary>
-	public interface IFlurlRequest : IHttpSettingsContainer
+	public interface IFlurlRequest : ISettingsContainer, IHeadersContainer
 	{
 		/// <summary>
 		/// Gets or sets the IFlurlClient to use when sending the request.
@@ -106,6 +106,7 @@ public IFlurlClient Client {
 			set {
 				_client = value;
 				Settings.Parent = _client?.Settings;
+				SyncHeaders(_client, this);
 			}
 		}
 
@@ -142,6 +143,15 @@ public Task<IFlurlResponse> SendAsync(HttpMethod verb, HttpContent content = nul
 			return Client.SendAsync(this, completionOption, cancellationToken);
 		}
 
+		internal static void SyncHeaders(IFlurlClient client, IFlurlRequest request) {
+			if (client == null || request == null) return;
+
+			foreach (var header in client.Headers.ToList()) {
+				if (!request.Headers.Contains(header.Name))
+					request.Headers.Add(header.Name, header.Value);
+			}
+		}
+
 		private void ApplyCookieJar(CookieJar jar) {
 			_jar = jar;
 			if (jar == null)
diff --git a/src/Flurl.Http/HeaderExtensions.cs b/src/Flurl.Http/HeaderExtensions.cs
deleted file mode 100644
index b6762246..00000000
--- a/src/Flurl.Http/HeaderExtensions.cs
+++ /dev/null
@@ -1,76 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Flurl.Util;
-
-namespace Flurl.Http
-{
-	/// <summary>
-	/// Fluent extension methods for working with HTTP request headers.
-	/// </summary>
-    public static class HeaderExtensions
-    {
-	    /// <summary>
-	    /// Sets an HTTP header to be sent with this IFlurlRequest or all requests made with this IFlurlClient.
-	    /// </summary>
-	    /// <param name="clientOrRequest">The IFlurlClient or IFlurlRequest.</param>
-	    /// <param name="name">HTTP header name.</param>
-	    /// <param name="value">HTTP header value.</param>
-	    /// <returns>This IFlurlClient or IFlurlRequest.</returns>
-	    public static T WithHeader<T>(this T clientOrRequest, string name, object value) where T : IHttpSettingsContainer {
-		    if (value == null)
-			    clientOrRequest.Headers.Remove(name);
-			else
-			    clientOrRequest.Headers.AddOrReplace(name, value.ToInvariantString().Trim());
-		    return clientOrRequest;
-	    }
-
-	    /// <summary>
-	    /// Sets HTTP headers based on property names/values of the provided object, or keys/values if object is a dictionary, to be sent with this IFlurlRequest or all requests made with this IFlurlClient.
-	    /// </summary>
-	    /// <param name="clientOrRequest">The IFlurlClient or IFlurlRequest.</param>
-	    /// <param name="headers">Names/values of HTTP headers to set. Typically an anonymous object or IDictionary.</param>
-	    /// <param name="replaceUnderscoreWithHyphen">If true, underscores in property names will be replaced by hyphens. Default is true.</param>
-	    /// <returns>This IFlurlClient or IFlurlRequest.</returns>
-	    public static T WithHeaders<T>(this T clientOrRequest, object headers, bool replaceUnderscoreWithHyphen = true) where T : IHttpSettingsContainer {
-		    if (headers == null)
-			    return clientOrRequest;
-
-			// underscore replacement only applies when object properties are parsed to kv pairs
-		    replaceUnderscoreWithHyphen = replaceUnderscoreWithHyphen && !(headers is string) && !(headers is IEnumerable);
-
-		    foreach (var kv in headers.ToKeyValuePairs()) {
-			    var key = replaceUnderscoreWithHyphen ? kv.Key.Replace("_", "-") : kv.Key;
-			    clientOrRequest.WithHeader(key, kv.Value);
-		    }
-
-		    return clientOrRequest;
-	    }
-
-	    /// <summary>
-	    /// Sets HTTP authorization header according to Basic Authentication protocol to be sent with this IFlurlRequest or all requests made with this IFlurlClient.
-	    /// </summary>
-	    /// <param name="clientOrRequest">The IFlurlClient or IFlurlRequest.</param>
-	    /// <param name="username">Username of authenticating user.</param>
-	    /// <param name="password">Password of authenticating user.</param>
-	    /// <returns>This IFlurlClient or IFlurlRequest.</returns>
-	    public static T WithBasicAuth<T>(this T clientOrRequest, string username, string password) where T : IHttpSettingsContainer {
-		    // http://stackoverflow.com/questions/14627399/setting-authorization-header-of-httpclient
-		    var encodedCreds = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{username}:{password}"));
-		    return clientOrRequest.WithHeader("Authorization", $"Basic {encodedCreds}");
-	    }
-
-	    /// <summary>
-	    /// Sets HTTP authorization header with acquired bearer token according to OAuth 2.0 specification to be sent with this IFlurlRequest or all requests made with this IFlurlClient.
-	    /// </summary>
-	    /// <param name="clientOrRequest">The IFlurlClient or IFlurlRequest.</param>
-	    /// <param name="token">The acquired bearer token to pass.</param>
-	    /// <returns>This IFlurlClient or IFlurlRequest.</returns>
-	    public static T WithOAuthBearerToken<T>(this T clientOrRequest, string token) where T : IHttpSettingsContainer {
-		    return clientOrRequest.WithHeader("Authorization", $"Bearer {token}");
-	    }
-    }
-}
diff --git a/src/Flurl.Http/IHeadersContainer.cs b/src/Flurl.Http/IHeadersContainer.cs
new file mode 100644
index 00000000..366f1b3f
--- /dev/null
+++ b/src/Flurl.Http/IHeadersContainer.cs
@@ -0,0 +1,84 @@
+using System;
+using System.Collections;
+using System.Text;
+using Flurl.Util;
+
+namespace Flurl.Http
+{
+	/// <summary>
+	/// A common interface for Flurl.Http objects that contain a collection of request headers.
+	/// </summary>
+	public interface IHeadersContainer
+	{
+		/// <summary>
+		/// A collection of request headers.
+		/// </summary>
+		INameValueList<string> Headers { get; }
+	}
+
+	/// <summary>
+	/// Fluent extension methods for working with HTTP request headers.
+	/// </summary>
+	public static class HeaderExtensions
+    {
+		/// <summary>
+		/// Sets an HTTP header associated with this request or client.
+		/// </summary>
+		/// <param name="obj">Object containing request headers.</param>
+		/// <param name="name">HTTP header name.</param>
+		/// <param name="value">HTTP header value.</param>
+		/// <returns>This headers container.</returns>
+		public static T WithHeader<T>(this T obj, string name, object value) where T : IHeadersContainer {
+		    if (value == null)
+			    obj.Headers.Remove(name);
+			else
+			    obj.Headers.AddOrReplace(name, value.ToInvariantString().Trim());
+		    return obj;
+	    }
+
+		/// <summary>
+		/// Sets HTTP headers based on property names/values of the provided object, or keys/values if object is a dictionary, associated with this request or client.
+		/// </summary>
+		/// <param name="obj">Object containing request headers.</param>
+		/// <param name="headers">Names/values of HTTP headers to set. Typically an anonymous object or IDictionary.</param>
+		/// <param name="replaceUnderscoreWithHyphen">If true, underscores in property names will be replaced by hyphens. Default is true.</param>
+		/// <returns>This headers container.</returns>
+		public static T WithHeaders<T>(this T obj, object headers, bool replaceUnderscoreWithHyphen = true) where T : IHeadersContainer {
+		    if (headers == null)
+			    return obj;
+
+			// underscore replacement only applies when object properties are parsed to kv pairs
+		    replaceUnderscoreWithHyphen = replaceUnderscoreWithHyphen && !(headers is string) && !(headers is IEnumerable);
+
+		    foreach (var kv in headers.ToKeyValuePairs()) {
+			    var key = replaceUnderscoreWithHyphen ? kv.Key.Replace("_", "-") : kv.Key;
+			    obj.WithHeader(key, kv.Value);
+		    }
+
+		    return obj;
+	    }
+
+		/// <summary>
+		/// Sets HTTP authorization header according to Basic Authentication protocol associated with this request or client.
+		/// </summary>
+		/// <param name="obj">Object containing request headers.</param>
+		/// <param name="username">Username of authenticating user.</param>
+		/// <param name="password">Password of authenticating user.</param>
+		/// <returns>This headers container.</returns>
+		public static T WithBasicAuth<T>(this T obj, string username, string password) where T : IHeadersContainer {
+		    // http://stackoverflow.com/questions/14627399/setting-authorization-header-of-httpclient
+		    var encodedCreds = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{username}:{password}"));
+		    return obj.WithHeader("Authorization", $"Basic {encodedCreds}");
+	    }
+
+		/// <summary>
+		/// Sets HTTP authorization header with acquired bearer token according to OAuth 2.0 specification associated with this request or client.
+		/// </summary>
+		/// <param name="obj">Object containing request headers.</param>
+		/// <param name="token">The acquired bearer token to pass.</param>
+		/// <returns>This headers container.</returns>
+		public static T WithOAuthBearerToken<T>(this T obj, string token) where T : IHeadersContainer {
+		    return obj.WithHeader("Authorization", $"Bearer {token}");
+	    }
+    }
+}
diff --git a/src/Flurl.Http/IHttpSettingsContainer.cs b/src/Flurl.Http/IHttpSettingsContainer.cs
deleted file mode 100644
index 50696c41..00000000
--- a/src/Flurl.Http/IHttpSettingsContainer.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-using System;
-using System.Collections.Generic;
-using Flurl.Http.Configuration;
-using Flurl.Util;
-
-namespace Flurl.Http
-{
-	/// <summary>
-	/// Defines stateful aspects (headers, cookies, etc) common to both IFlurlClient and IFlurlRequest
-	/// </summary>
-	public interface IHttpSettingsContainer
-	{
-	    /// <summary>
-	    /// Gets the FlurlHttpSettings object used by this client or request.
-	    /// </summary>
-	    FlurlHttpSettings Settings { get; }
-
-		/// <summary>
-		/// Collection of headers sent on this request or all requests using this client.
-		/// </summary>
-		INameValueList<string> Headers { get; }
-    }
-}
diff --git a/src/Flurl.Http/SettingsExtensions.cs b/src/Flurl.Http/ISettingsContainer.cs
similarity index 69%
rename from src/Flurl.Http/SettingsExtensions.cs
rename to src/Flurl.Http/ISettingsContainer.cs
index b5c3a06f..2c8a6d0b 100644
--- a/src/Flurl.Http/SettingsExtensions.cs
+++ b/src/Flurl.Http/ISettingsContainer.cs
@@ -7,50 +7,50 @@
 namespace Flurl.Http
 {
 	/// <summary>
-	/// Fluent extension methods for tweaking FlurlHttpSettings
+	/// A common interface for Flurl.Http objects that contain a collection of request settings.
 	/// </summary>
-	public static class SettingsExtensions
+	public interface ISettingsContainer
 	{
 		/// <summary>
-		/// Change FlurlHttpSettings for this IFlurlClient.
+		/// A collection request settings.
 		/// </summary>
-		/// <param name="client">The IFlurlClient.</param>
-		/// <param name="action">Action defining the settings changes.</param>
-		/// <returns>The IFlurlClient with the modified Settings</returns>
-		public static IFlurlClient WithSettings(this IFlurlClient client, Action<FlurlHttpSettings> action) {
-			action(client.Settings);
-			return client;
-		}
+		FlurlHttpSettings Settings { get; }
+	}
 
+	/// <summary>
+	/// Fluent extension methods for tweaking FlurlHttpSettings
+	/// </summary>
+	public static class SettingsExtensions
+	{
 		/// <summary>
-		/// Change FlurlHttpSettings for this IFlurlRequest.
+		/// Change FlurlHttpSettings for this request, client, or test context.
 		/// </summary>
-		/// <param name="request">The IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="action">Action defining the settings changes.</param>
-		/// <returns>The IFlurlRequest with the modified Settings</returns>
-		public static IFlurlRequest WithSettings(this IFlurlRequest request, Action<FlurlHttpSettings> action) {
-			action(request.Settings);
-			return request;
+		/// <returns>This settings container.</returns>
+		public static T WithSettings<T>(this T obj, Action<FlurlHttpSettings> action) where T : ISettingsContainer {
+			action(obj.Settings);
+			return obj;
 		}
 
 		/// <summary>
-		/// Sets the timeout for this IFlurlRequest or all requests made with this IFlurlClient.
+		/// Sets the timeout for this request, client, or test context.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="timespan">Time to wait before the request times out.</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T WithTimeout<T>(this T obj, TimeSpan timespan) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T WithTimeout<T>(this T obj, TimeSpan timespan) where T : ISettingsContainer {
 			obj.Settings.Timeout = timespan;
 			return obj;
 		}
 
 		/// <summary>
-		/// Sets the timeout for this IFlurlRequest or all requests made with this IFlurlClient.
+		/// Sets the timeout for this request, client, or test context.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="seconds">Seconds to wait before the request times out.</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T WithTimeout<T>(this T obj, int seconds) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T WithTimeout<T>(this T obj, int seconds) where T : ISettingsContainer {
 			obj.Settings.Timeout = TimeSpan.FromSeconds(seconds);
 			return obj;
 		}
@@ -58,10 +58,10 @@ public static T WithTimeout<T>(this T obj, int seconds) where T : IHttpSettingsC
 		/// <summary>
 		/// Adds a pattern representing an HTTP status code or range of codes which (in addition to 2xx) will NOT result in a FlurlHttpException being thrown.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="pattern">Examples: "3xx", "100,300,600", "100-299,6xx"</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T AllowHttpStatus<T>(this T obj, string pattern) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T AllowHttpStatus<T>(this T obj, string pattern) where T : ISettingsContainer {
 			if (!string.IsNullOrWhiteSpace(pattern)) {
 				var current = obj.Settings.AllowedHttpStatusRange;
 				if (string.IsNullOrWhiteSpace(current))
@@ -75,10 +75,10 @@ public static T AllowHttpStatus<T>(this T obj, string pattern) where T : IHttpSe
 		/// <summary>
 		/// Adds an <see cref="HttpStatusCode" /> which (in addition to 2xx) will NOT result in a FlurlHttpException being thrown.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="statusCodes">Examples: HttpStatusCode.NotFound</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T AllowHttpStatus<T>(this T obj, params HttpStatusCode[] statusCodes) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T AllowHttpStatus<T>(this T obj, params HttpStatusCode[] statusCodes) where T : ISettingsContainer {
 			var pattern = string.Join(",", statusCodes.Select(c => (int)c));
 			return AllowHttpStatus(obj, pattern);
 		}
@@ -86,9 +86,9 @@ public static T AllowHttpStatus<T>(this T obj, params HttpStatusCode[] statusCod
 		/// <summary>
 		/// Prevents a FlurlHttpException from being thrown on any completed response, regardless of the HTTP status code.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T AllowAnyHttpStatus<T>(this T obj) where T : IHttpSettingsContainer {
+		/// <param name="obj">Object containing settings.</param>
+		/// <returns>This settings container.</returns>
+		public static T AllowAnyHttpStatus<T>(this T obj) where T : ISettingsContainer {
 			obj.Settings.AllowedHttpStatusRange = "*";
 			return obj;
 		}
@@ -96,10 +96,10 @@ public static T AllowAnyHttpStatus<T>(this T obj) where T : IHttpSettingsContain
 		/// <summary>
 		/// Configures whether redirects are automatically followed.
 		/// </summary>
-		/// <param name="obj">The IFlurlClient or IFlurlRequest.</param>
+		/// <param name="obj">Object containing settings.</param>
 		/// <param name="enabled">true if Flurl should automatically send a new request to the redirect URL, false if it should not.</param>
-		/// <returns>This IFlurlClient or IFlurlRequest.</returns>
-		public static T WithAutoRedirect<T>(this T obj, bool enabled) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T WithAutoRedirect<T>(this T obj, bool enabled) where T : ISettingsContainer {
 			obj.Settings.Redirects.Enabled = enabled;
 			return obj;
 		}
@@ -107,7 +107,8 @@ public static T WithAutoRedirect<T>(this T obj, bool enabled) where T : IHttpSet
 		/// <summary>
 		/// Sets a callback that is invoked immediately before every HTTP request is sent.
 		/// </summary>
-		public static T BeforeCall<T>(this T obj, Action<FlurlCall> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T BeforeCall<T>(this T obj, Action<FlurlCall> act) where T : ISettingsContainer {
 			obj.Settings.BeforeCall = act;
 			return obj;
 		}
@@ -115,7 +116,8 @@ public static T BeforeCall<T>(this T obj, Action<FlurlCall> act) where T : IHttp
 		/// <summary>
 		/// Sets a callback that is invoked asynchronously immediately before every HTTP request is sent.
 		/// </summary>
-		public static T BeforeCall<T>(this T obj, Func<FlurlCall, Task> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T BeforeCall<T>(this T obj, Func<FlurlCall, Task> act) where T : ISettingsContainer {
 			obj.Settings.BeforeCallAsync = act;
 			return obj;
 		}
@@ -123,7 +125,8 @@ public static T BeforeCall<T>(this T obj, Func<FlurlCall, Task> act) where T : I
 		/// <summary>
 		/// Sets a callback that is invoked immediately after every HTTP response is received.
 		/// </summary>
-		public static T AfterCall<T>(this T obj, Action<FlurlCall> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T AfterCall<T>(this T obj, Action<FlurlCall> act) where T : ISettingsContainer {
 			obj.Settings.AfterCall = act;
 			return obj;
 		}
@@ -131,7 +134,8 @@ public static T AfterCall<T>(this T obj, Action<FlurlCall> act) where T : IHttpS
 		/// <summary>
 		/// Sets a callback that is invoked asynchronously immediately after every HTTP response is received.
 		/// </summary>
-		public static T AfterCall<T>(this T obj, Func<FlurlCall, Task> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T AfterCall<T>(this T obj, Func<FlurlCall, Task> act) where T : ISettingsContainer {
 			obj.Settings.AfterCallAsync = act;
 			return obj;
 		}
@@ -140,7 +144,8 @@ public static T AfterCall<T>(this T obj, Func<FlurlCall, Task> act) where T : IH
 		/// Sets a callback that is invoked when an error occurs during any HTTP call, including when any non-success
 		/// HTTP status code is returned in the response. Response should be null-checked if used in the event handler.
 		/// </summary>
-		public static T OnError<T>(this T obj, Action<FlurlCall> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T OnError<T>(this T obj, Action<FlurlCall> act) where T : ISettingsContainer {
 			obj.Settings.OnError = act;
 			return obj;
 		}
@@ -149,7 +154,8 @@ public static T OnError<T>(this T obj, Action<FlurlCall> act) where T : IHttpSet
 		/// Sets a callback that is invoked asynchronously when an error occurs during any HTTP call, including when any non-success
 		/// HTTP status code is returned in the response. Response should be null-checked if used in the event handler.
 		/// </summary>
-		public static T OnError<T>(this T obj, Func<FlurlCall, Task> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T OnError<T>(this T obj, Func<FlurlCall, Task> act) where T : ISettingsContainer {
 			obj.Settings.OnErrorAsync = act;
 			return obj;
 		}
@@ -159,7 +165,8 @@ public static T OnError<T>(this T obj, Func<FlurlCall, Task> act) where T : IHtt
 		/// You can inspect/manipulate the call.Redirect object to determine what will happen next.
 		/// An auto-redirect will only happen if call.Redirect.Follow is true upon exiting the callback.
 		/// </summary>
-		public static T OnRedirect<T>(this T obj, Action<FlurlCall> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T OnRedirect<T>(this T obj, Action<FlurlCall> act) where T : ISettingsContainer {
 			obj.Settings.OnRedirect = act;
 			return obj;
 		}
@@ -169,7 +176,8 @@ public static T OnRedirect<T>(this T obj, Action<FlurlCall> act) where T : IHttp
 		/// You can inspect/manipulate the call.Redirect object to determine what will happen next.
 		/// An auto-redirect will only happen if call.Redirect.Follow is true upon exiting the callback.
 		/// </summary>
-		public static T OnRedirect<T>(this T obj, Func<FlurlCall, Task> act) where T : IHttpSettingsContainer {
+		/// <returns>This settings container.</returns>
+		public static T OnRedirect<T>(this T obj, Func<FlurlCall, Task> act) where T : ISettingsContainer {
 			obj.Settings.OnRedirectAsync = act;
 			return obj;
 		}
diff --git a/src/Flurl.Http/Testing/HttpTest.cs b/src/Flurl.Http/Testing/HttpTest.cs
index 43a0c0a6..cf221944 100644
--- a/src/Flurl.Http/Testing/HttpTest.cs
+++ b/src/Flurl.Http/Testing/HttpTest.cs
@@ -3,7 +3,6 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
-using System.Net.Http;
 using Flurl.Http.Configuration;
 
 namespace Flurl.Http.Testing
@@ -13,7 +12,7 @@ namespace Flurl.Http.Testing
 	/// queue, call log, and assertion helpers for use in Arrange/Act/Assert style tests.
 	/// </summary>
 	[Serializable]
-	public class HttpTest : HttpTestSetup, IDisposable
+	public class HttpTest : HttpTestSetup, ISettingsContainer, IDisposable
 	{
 		private readonly ConcurrentQueue<FlurlCall> _calls = new();
 		private readonly List<FilteredHttpTestSetup> _filteredSetups = new();
@@ -38,16 +37,6 @@ public HttpTest() : base(new FlurlHttpSettings()) {
 		/// </summary>
 		public IReadOnlyList<FlurlCall> CallLog => new ReadOnlyCollection<FlurlCall>(_calls.ToList());
 
-		/// <summary>
-		/// Change FlurlHttpSettings for the scope of this HttpTest.
-		/// </summary>
-		/// <param name="action">Action defining the settings changes.</param>
-		/// <returns>This HttpTest</returns>
-		public HttpTest WithSettings(Action<FlurlHttpSettings> action) {
-			action(Settings);
-			return this;
-		}
-
 		/// <summary>
 		/// Fluently creates and returns a new request-specific test setup. 
 		/// </summary>
diff --git a/src/Flurl.Http/Testing/HttpTestSetup.cs b/src/Flurl.Http/Testing/HttpTestSetup.cs
index 4439ce30..698339b0 100644
--- a/src/Flurl.Http/Testing/HttpTestSetup.cs
+++ b/src/Flurl.Http/Testing/HttpTestSetup.cs
@@ -16,7 +16,7 @@ namespace Flurl.Http.Testing
 	/// </summary>
 	public abstract class HttpTestSetup
 	{
-		private readonly List<Func<HttpResponseMessage>> _responses = new List<Func<HttpResponseMessage>>();
+		private readonly List<Func<HttpResponseMessage>> _responses = new();
 
 		private int _respIndex = 0;
 		private bool _allowRealHttp = false;
diff --git a/test/Flurl.Test/Http/FlurlClientBuilderTests.cs b/test/Flurl.Test/Http/FlurlClientBuilderTests.cs
index fba59818..efdcae5f 100644
--- a/test/Flurl.Test/Http/FlurlClientBuilderTests.cs
+++ b/test/Flurl.Test/Http/FlurlClientBuilderTests.cs
@@ -12,13 +12,6 @@ namespace Flurl.Test.Http
 	[TestFixture]
 	public class FlurlClientBuilderTests
 	{
-		[Test]
-		public void can_configure_settings() {
-			var builder = new FlurlClientBuilder();
-			var cli = builder.WithSettings(s => s.HttpVersion = "3.0").Build();
-			Assert.AreEqual("3.0", cli.Settings.HttpVersion);
-		}
-
 		[Test]
 		public void can_configure_HttpClient() {
 			var builder = new FlurlClientBuilder();
diff --git a/test/Flurl.Test/Http/FlurlClientTests.cs b/test/Flurl.Test/Http/FlurlClientTests.cs
index 87dddc34..2936b08b 100644
--- a/test/Flurl.Test/Http/FlurlClientTests.cs
+++ b/test/Flurl.Test/Http/FlurlClientTests.cs
@@ -70,6 +70,13 @@ public void can_create_request_with_base_url_and_no_segments() {
 			Assert.AreEqual("http://myapi.com", req.Url.ToString());
 		}
 
+		[Test]
+		public void can_create_request_with_Uri() {
+			var uri = new System.Uri("http://www.mysite.com/foo?x=1");
+			var req = new FlurlClient().Request(uri);
+			Assert.AreEqual(uri.ToString(), req.Url.ToString());
+		}
+
 		[Test]
 		public void cannot_send_invalid_request() {
 			var cli = new FlurlClient();
diff --git a/test/Flurl.Test/Http/HeadersTests.cs b/test/Flurl.Test/Http/HeadersTests.cs
new file mode 100644
index 00000000..684ddd40
--- /dev/null
+++ b/test/Flurl.Test/Http/HeadersTests.cs
@@ -0,0 +1,158 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Flurl.Http;
+using Flurl.Http.Configuration;
+using Flurl.Http.Testing;
+using NUnit.Framework;
+
+namespace Flurl.Test.Http
+{
+	/// <summary>
+	/// A Headers collection is available on IFlurlRequest, IFlurlClient, and IFlurlBuilder.
+	/// This abstract class allows the same tests to be run against all 3.
+	/// </summary>
+	public abstract class HeadersTestsBase<T> where T : IHeadersContainer
+	{
+		protected abstract T CreateContainer();
+		protected abstract IFlurlRequest GetRequest(T container);
+
+		[Test]
+		public void can_set_header() {
+			var c = CreateContainer();
+			c.WithHeader("a", 1);
+			Assert.AreEqual(("a", "1"), GetRequest(c).Headers.Single());
+		}
+
+		[Test]
+		public void can_set_headers_from_anon_object() {
+			var c = CreateContainer();
+			// null values shouldn't be added
+			c.WithHeaders(new { a = "b", one = 2, three = (object)null });
+
+			var req = GetRequest(c);
+			Assert.AreEqual(2, req.Headers.Count);
+			Assert.IsTrue(req.Headers.Contains("a", "b"));
+			Assert.IsTrue(req.Headers.Contains("one", "2"));
+		}
+
+		[Test]
+		public void can_remove_header_by_setting_null() {
+			var c = CreateContainer();
+			c.WithHeaders(new { a = 1, b = 2 });
+			Assert.AreEqual(2, GetRequest(c).Headers.Count);
+
+			c.WithHeader("b", null);
+
+			var req = GetRequest(c);
+			Assert.AreEqual(1, req.Headers.Count);
+			Assert.IsFalse(req.Headers.Contains("b"));
+		}
+
+		[Test]
+		public void can_set_headers_from_dictionary() {
+			var c = CreateContainer();
+			c.WithHeaders(new Dictionary<string, object> { { "a", "b" }, { "one", 2 } });
+
+			var req = GetRequest(c);
+			Assert.AreEqual(2, req.Headers.Count);
+			Assert.IsTrue(req.Headers.Contains("a", "b"));
+			Assert.IsTrue(req.Headers.Contains("one", "2"));
+		}
+
+		[Test]
+		public void underscores_in_properties_convert_to_hyphens_in_header_names() {
+			var c = CreateContainer();
+			c.WithHeaders(new { User_Agent = "Flurl", Cache_Control = "no-cache" });
+
+			var req = GetRequest(c);
+			Assert.IsTrue(req.Headers.Contains("User-Agent"));
+			Assert.IsTrue(req.Headers.Contains("Cache-Control"));
+
+			// make sure we can disable the behavior
+			c.WithHeaders(new { no_i_really_want_underscores = "foo" }, false);
+			Assert.IsTrue(GetRequest(c).Headers.Contains("no_i_really_want_underscores"));
+
+			// dictionaries don't get this behavior since you can use hyphens explicitly
+			c.WithHeaders(new Dictionary<string, string> { { "exclude_dictionaries", "bar" } });
+			Assert.IsTrue(GetRequest(c).Headers.Contains("exclude_dictionaries"));
+
+			// same with strings
+			c.WithHeaders("exclude_strings=123");
+			Assert.IsTrue(GetRequest(c).Headers.Contains("exclude_strings"));
+		}
+
+		[Test]
+		public void header_names_are_case_insensitive() {
+			var c = CreateContainer();
+			c.WithHeader("a", 1).WithHeader("A", 2);
+
+			var req = GetRequest(c);
+			Assert.AreEqual(1, req.Headers.Count);
+			Assert.AreEqual("A", req.Headers.Single().Name);
+			Assert.AreEqual("2", req.Headers.Single().Value);
+		}
+
+		[Test] // #623
+		public async Task header_values_are_trimmed() {
+			var c = CreateContainer();
+			c.WithHeader("a", "   1 \t\r\n");
+			c.Headers.Add("b", "   2   ");
+
+			var req = GetRequest(c);
+			Assert.AreEqual(2, req.Headers.Count);
+			Assert.AreEqual("1", req.Headers[0].Value);
+			// Not trimmed when added directly to Headers collection (implementation seemed like overkill),
+			// but below we'll make sure it happens on HttpRequestMessage when request is sent.
+			Assert.AreEqual("   2   ", req.Headers[1].Value);
+
+			using var test = new HttpTest();
+			await GetRequest(c).GetAsync();
+			var sentHeaders = test.CallLog[0].HttpRequestMessage.Headers;
+			Assert.AreEqual("1", sentHeaders.GetValues("a").Single());
+			Assert.AreEqual("2", sentHeaders.GetValues("b").Single());
+		}
+
+		[Test]
+		public void can_setup_oauth_bearer_token() {
+			var c = CreateContainer();
+			c.WithOAuthBearerToken("mytoken");
+
+			var req = GetRequest(c);
+			Assert.AreEqual(1, req.Headers.Count);
+			Assert.IsTrue(req.Headers.Contains("Authorization", "Bearer mytoken"));
+		}
+
+		[Test]
+		public void can_setup_basic_auth() {
+			var c = CreateContainer();
+			c.WithBasicAuth("user", "pass");
+
+			var req = GetRequest(c);
+			Assert.AreEqual(1, req.Headers.Count);
+			Assert.IsTrue(req.Headers.Contains("Authorization", "Basic dXNlcjpwYXNz"));
+		}
+	}
+
+	[TestFixture]
+	public class RequestHeadersTests : HeadersTestsBase<IFlurlRequest>
+	{
+		protected override IFlurlRequest CreateContainer() => new FlurlRequest("http://api.com");
+		protected override IFlurlRequest GetRequest(IFlurlRequest req) => req;
+	}
+
+	[TestFixture]
+	public class ClientHeadersTests : HeadersTestsBase<IFlurlClient>
+	{
+		protected override IFlurlClient CreateContainer() => new FlurlClient();
+		protected override IFlurlRequest GetRequest(IFlurlClient cli) => cli.Request("http://api.com");
+	}
+
+	[TestFixture]
+	public class ClientBuilderHeadersTests : HeadersTestsBase<IFlurlClientBuilder>
+	{
+		protected override IFlurlClientBuilder CreateContainer() => new FlurlClientBuilder();
+		protected override IFlurlRequest GetRequest(IFlurlClientBuilder builder) => builder.Build().Request("http://api.com");
+	}
+}
diff --git a/test/Flurl.Test/Http/SettingsExtensionsTests.cs b/test/Flurl.Test/Http/SettingsExtensionsTests.cs
deleted file mode 100644
index 96cb170e..00000000
--- a/test/Flurl.Test/Http/SettingsExtensionsTests.cs
+++ /dev/null
@@ -1,210 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net;
-using System.Threading.Tasks;
-using Flurl.Http;
-using Flurl.Http.Testing;
-using NUnit.Framework;
-
-namespace Flurl.Test.Http
-{
-	// IFlurlClient and IFlurlRequest both implement IHttpSettingsContainer, which defines a number
-	// of settings-related extension methods. This abstract test class allows those methods to be
-	// tested against both both client-level and request-level implementations.
-	public abstract class SettingsExtensionsTests<T> where T : IHttpSettingsContainer
-	{
-		protected abstract T GetSettingsContainer();
-		protected abstract IFlurlRequest GetRequest(T sc);
-
-		[Test]
-		public void can_set_timeout() {
-			var sc = GetSettingsContainer().WithTimeout(TimeSpan.FromSeconds(15));
-			Assert.AreEqual(TimeSpan.FromSeconds(15), sc.Settings.Timeout);
-		}
-
-		[Test]
-		public void can_set_timeout_in_seconds() {
-			var sc = GetSettingsContainer().WithTimeout(15);
-			Assert.AreEqual(sc.Settings.Timeout, TimeSpan.FromSeconds(15));
-		}
-
-		[Test]
-		public void can_set_header() {
-			var sc = GetSettingsContainer().WithHeader("a", 1);
-			Assert.AreEqual(("a", "1"), sc.Headers.Single());
-		}
-
-		[Test]
-		public void can_set_headers_from_anon_object() {
-			// null values shouldn't be added
-			var sc = GetSettingsContainer().WithHeaders(new { a = "b", one = 2, three = (object)null });
-			Assert.AreEqual(2, sc.Headers.Count);
-			Assert.IsTrue(sc.Headers.Contains("a", "b"));
-			Assert.IsTrue(sc.Headers.Contains("one", "2"));
-		}
-
-		[Test]
-		public void can_remove_header_by_setting_null() {
-			var sc = GetSettingsContainer().WithHeaders(new { a = 1, b = 2 });
-			Assert.AreEqual(2, sc.Headers.Count);
-			sc.WithHeader("b", null);
-			Assert.AreEqual(1, sc.Headers.Count);
-			Assert.IsFalse(sc.Headers.Contains("b"));
-		}
-
-		[Test]
-		public void can_set_headers_from_dictionary() {
-			var sc = GetSettingsContainer().WithHeaders(new Dictionary<string, object> { { "a", "b" }, { "one", 2 } });
-			Assert.AreEqual(2, sc.Headers.Count);
-			Assert.IsTrue(sc.Headers.Contains("a", "b"));
-			Assert.IsTrue(sc.Headers.Contains("one", "2"));
-		}
-
-		[Test]
-		public void underscores_in_properties_convert_to_hyphens_in_header_names() {
-			var sc = GetSettingsContainer().WithHeaders(new { User_Agent = "Flurl", Cache_Control = "no-cache" });
-			Assert.IsTrue(sc.Headers.Contains("User-Agent"));
-			Assert.IsTrue(sc.Headers.Contains("Cache-Control"));
-
-			// make sure we can disable the behavior
-			sc.WithHeaders(new { no_i_really_want_underscores = "foo" }, false);
-			Assert.IsTrue(sc.Headers.Contains("no_i_really_want_underscores"));
-
-			// dictionaries don't get this behavior since you can use hyphens explicitly
-			sc.WithHeaders(new Dictionary<string, string> { { "exclude_dictionaries", "bar" } });
-			Assert.IsTrue(sc.Headers.Contains("exclude_dictionaries"));
-
-			// same with strings
-			sc.WithHeaders("exclude_strings=123");
-			Assert.IsTrue(sc.Headers.Contains("exclude_strings"));
-		}
-
-		[Test]
-		public void header_names_are_case_insensitive() {
-			var sc = GetSettingsContainer().WithHeader("a", 1).WithHeader("A", 2);
-			Assert.AreEqual(1, sc.Headers.Count);
-			Assert.AreEqual("A", sc.Headers.Single().Name);
-			Assert.AreEqual("2", sc.Headers.Single().Value);
-		}
-
-		[Test] // #623
-		public async Task header_values_are_trimmed() {
-			var sc = GetSettingsContainer().WithHeader("a", "   1 \t\r\n");
-			sc.Headers.Add("b", "   2   ");
-
-			Assert.AreEqual(2, sc.Headers.Count);
-			Assert.AreEqual("1", sc.Headers[0].Value);
-			// Not trimmed when added directly to Headers collection (implementation seemed like overkill),
-			// but below we'll make sure it happens on HttpRequestMessage when request is sent.
-			Assert.AreEqual("   2   ", sc.Headers[1].Value);
-
-			using (var test = new HttpTest()) {
-				await GetRequest(sc).GetAsync();
-				var sentHeaders = test.CallLog[0].HttpRequestMessage.Headers;
-				Assert.AreEqual("1", sentHeaders.GetValues("a").Single());
-				Assert.AreEqual("2", sentHeaders.GetValues("b").Single());
-			}
-		}
-
-		[Test]
-		public void can_setup_oauth_bearer_token() {
-			var sc = GetSettingsContainer().WithOAuthBearerToken("mytoken");
-			Assert.AreEqual(1, sc.Headers.Count);
-			Assert.IsTrue(sc.Headers.Contains("Authorization", "Bearer mytoken"));
-		}
-
-		[Test]
-		public void can_setup_basic_auth() {
-			var sc = GetSettingsContainer().WithBasicAuth("user", "pass");
-			Assert.AreEqual(1, sc.Headers.Count);
-			Assert.IsTrue(sc.Headers.Contains("Authorization", "Basic dXNlcjpwYXNz"));
-		}
-
-		[Test]
-		public async Task can_allow_specific_http_status() {
-			using var test = new HttpTest();
-			test.RespondWith("Nothing to see here", 404);
-			var sc = GetSettingsContainer().AllowHttpStatus(HttpStatusCode.Conflict, HttpStatusCode.NotFound);
-			await GetRequest(sc).DeleteAsync(); // no exception = pass
-		}
-
-		[Test]
-		public async Task allow_specific_http_status_also_allows_2xx() {
-			using var test = new HttpTest();
-			test.RespondWith("I'm just an innocent 2xx, I should never fail!", 201);
-			var sc = GetSettingsContainer().AllowHttpStatus(HttpStatusCode.Conflict, HttpStatusCode.NotFound);
-			await GetRequest(sc).GetAsync(); // no exception = pass
-		}
-
-		[Test]
-		public void can_clear_non_success_status() {
-			using var test = new HttpTest();
-			test.RespondWith("I'm a teapot", 418);
-			// allow 4xx
-			var sc = GetSettingsContainer().AllowHttpStatus("4xx");
-			// but then disallow it
-			sc.Settings.AllowedHttpStatusRange = null;
-			Assert.ThrowsAsync<FlurlHttpException>(async () => await GetRequest(sc).GetAsync());
-		}
-
-		[Test]
-		public async Task can_allow_any_http_status() {
-			using var test = new HttpTest();
-			test.RespondWith("epic fail", 500);
-			try {
-				var sc = GetSettingsContainer().AllowAnyHttpStatus();
-				var result = await GetRequest(sc).GetAsync();
-				Assert.AreEqual(500, result.StatusCode);
-			}
-			catch (Exception) {
-				Assert.Fail("Exception should not have been thrown.");
-			}
-		}
-	}
-
-	[TestFixture, Parallelizable]
-	public class ClientSettingsExtensionsTests : SettingsExtensionsTests<IFlurlClient>
-	{
-		protected override IFlurlClient GetSettingsContainer() => new FlurlClient();
-		protected override IFlurlRequest GetRequest(IFlurlClient client) => client.Request("http://api.com");
-
-		[Test]
-		public void WithUrl_shares_client_but_not_Url() {
-			var cli = new FlurlClient().WithHeader("myheader", "123");
-			var req1 = cli.Request("http://www.api.com/for-req1");
-			var req2 = cli.Request("http://www.api.com/for-req2");
-			var req3 = cli.Request("http://www.api.com/for-req3");
-
-			CollectionAssert.AreEquivalent(req1.Headers, req2.Headers);
-			CollectionAssert.AreEquivalent(req1.Headers, req3.Headers);
-			var urls = new[] { req1, req2, req3 }.Select(c => c.Url.ToString());
-			CollectionAssert.AllItemsAreUnique(urls);
-		}
-
-		[Test]
-		public void can_use_uri_with_WithUrl() {
-			var uri = new System.Uri("http://www.mysite.com/foo?x=1");
-			var req = new FlurlClient().Request(uri);
-			Assert.AreEqual(uri.ToString(), req.Url.ToString());
-		}
-
-		[Test]
-		public void can_override_settings_fluently() {
-			using (var test = new HttpTest()) {
-				var cli = new FlurlClient().WithSettings(s => s.AllowedHttpStatusRange = "*");
-				test.RespondWith("epic fail", 500);
-				var req = "http://www.api.com".WithSettings(c => c.AllowedHttpStatusRange = "2xx");
-				req.Client = cli; // client-level settings shouldn't win
-				Assert.ThrowsAsync<FlurlHttpException>(async () => await req.GetAsync());
-			}
-		}
-	}
-
-	[TestFixture, Parallelizable]
-	public class RequestSettingsExtensionsTests : SettingsExtensionsTests<IFlurlRequest>
-	{
-		protected override IFlurlRequest GetSettingsContainer() => new FlurlRequest("http://api.com");
-		protected override IFlurlRequest GetRequest(IFlurlRequest req) => req;
-	}
-}
\ No newline at end of file
diff --git a/test/Flurl.Test/Http/SettingsTests.cs b/test/Flurl.Test/Http/SettingsTests.cs
index 64e2f7cd..9ccbe4da 100644
--- a/test/Flurl.Test/Http/SettingsTests.cs
+++ b/test/Flurl.Test/Http/SettingsTests.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Net;
 using System.Threading.Tasks;
 using Flurl.Http;
 using Flurl.Http.Configuration;
@@ -9,22 +10,23 @@
 namespace Flurl.Test.Http
 {
 	/// <summary>
-	/// FlurlHttpSettings are available at the test, client, and request level. This abstract class
-	/// allows the same tests to be run against settings at all 4 levels.
+	/// A Settings collection is available on IFlurlRequest, IFlurlClient, IFlurlBuilder, and HttpTest.
+	/// This abstract class allows the same tests to be run against all 4.
 	/// </summary>
-	public abstract class SettingsTestsBase
+	public abstract class SettingsTestsBase<T> where T : ISettingsContainer
 	{
-		protected abstract FlurlHttpSettings GetSettings();
-		protected abstract IFlurlRequest GetRequest();
+		protected abstract T CreateContainer();
+		protected abstract IFlurlRequest GetRequest(T container);
 
 		[Test]
 		public async Task can_set_http_version() {
-			Assert.AreEqual("1.1", GetSettings().HttpVersion); // default
-
 			using var test = new HttpTest();
 
-			GetSettings().HttpVersion = "2.0";
-			var req = GetRequest();
+			var c = CreateContainer();
+			Assert.AreEqual("1.1", c.Settings.HttpVersion); // default
+
+			c.Settings.HttpVersion = "2.0";
+			var req = GetRequest(c);
 			Assert.AreEqual("2.0", req.Settings.HttpVersion);
 
 			Version versionUsed = null;
@@ -37,17 +39,18 @@ await req
 
 		[Test]
 		public void cannot_set_invalid_http_version() {
-			Assert.Throws<ArgumentException>(() => GetSettings().HttpVersion = "foo");
+			Assert.Throws<ArgumentException>(() => CreateContainer().Settings.HttpVersion = "foo");
 		}
 
 		[Test]
 		public async Task can_allow_non_success_status() {
 			using var test = new HttpTest();
 
-			GetSettings().AllowedHttpStatusRange = "4xx";
+			var c = CreateContainer();
+			c.Settings.AllowedHttpStatusRange = "4xx";
 			test.RespondWith("I'm a teapot", 418);
 			try {
-				var result = await GetRequest().GetAsync();
+				var result = await GetRequest(c).GetAsync();
 				Assert.AreEqual(418, result.StatusCode);
 			}
 			catch (Exception) {
@@ -61,12 +64,13 @@ public async Task can_set_pre_callback() {
 			using var test = new HttpTest();
 
 			test.RespondWith("ok");
-			GetSettings().BeforeCall = call => {
+			var c = CreateContainer();
+			c.Settings.BeforeCall = call => {
 				Assert.Null(call.Response); // verifies that callback is running before HTTP call is made
 				callbackCalled = true;
 			};
 			Assert.IsFalse(callbackCalled);
-			await GetRequest().GetAsync();
+			await GetRequest(c).GetAsync();
 			Assert.IsTrue(callbackCalled);
 		}
 
@@ -76,12 +80,13 @@ public async Task can_set_post_callback() {
 			using var test = new HttpTest();
 
 			test.RespondWith("ok");
-			GetSettings().AfterCall = call => {
+			var c = CreateContainer();
+			c.Settings.AfterCall = call => {
 				Assert.NotNull(call.Response); // verifies that callback is running after HTTP call is made
 				callbackCalled = true;
 			};
 			Assert.IsFalse(callbackCalled);
-			await GetRequest().GetAsync();
+			await GetRequest(c).GetAsync();
 			Assert.IsTrue(callbackCalled);
 		}
 
@@ -92,14 +97,15 @@ public async Task can_set_error_callback(bool markExceptionHandled) {
 			using var test = new HttpTest();
 
 			test.RespondWith("server error", 500);
-			GetSettings().OnError = call => {
+			var c = CreateContainer();
+			c.Settings.OnError = call => {
 				Assert.NotNull(call.Response); // verifies that callback is running after HTTP call is made
 				callbackCalled = true;
 				call.ExceptionHandled = markExceptionHandled;
 			};
 			Assert.IsFalse(callbackCalled);
 			try {
-				await GetRequest().GetAsync();
+				await GetRequest(c).GetAsync();
 				Assert.IsTrue(callbackCalled, "OnError was never called");
 				Assert.IsTrue(markExceptionHandled, "ExceptionHandled was marked false in callback, but exception was not propagated.");
 			}
@@ -113,12 +119,13 @@ public async Task can_set_error_callback(bool markExceptionHandled) {
 		public async Task can_disable_exception_behavior() {
 			using var test = new HttpTest();
 
-			GetSettings().OnError = call => {
+			var c = CreateContainer();
+			c.Settings.OnError = call => {
 				call.ExceptionHandled = true;
 			};
 			test.RespondWith("server error", 500);
 			try {
-				var result = await GetRequest().GetAsync();
+				var result = await GetRequest(c).GetAsync();
 				Assert.AreEqual(500, result.StatusCode);
 			}
 			catch (FlurlHttpException) {
@@ -128,22 +135,27 @@ public async Task can_disable_exception_behavior() {
 
 		[Test]
 		public void can_reset_defaults() {
-			GetSettings().JsonSerializer = null;
-			GetSettings().Redirects.Enabled = false;
-			GetSettings().BeforeCall = (call) => Console.WriteLine("Before!");
-			GetSettings().Redirects.MaxAutoRedirects = 5;
+			var c = CreateContainer();
+
+			c.Settings.JsonSerializer = null;
+			c.Settings.Redirects.Enabled = false;
+			c.Settings.BeforeCall = (call) => Console.WriteLine("Before!");
+			c.Settings.Redirects.MaxAutoRedirects = 5;
 
-			Assert.IsNull(GetSettings().JsonSerializer);
-			Assert.IsFalse(GetSettings().Redirects.Enabled);
-			Assert.IsNotNull(GetSettings().BeforeCall);
-			Assert.AreEqual(5, GetSettings().Redirects.MaxAutoRedirects);
+			var req = GetRequest(c);
 
-			GetSettings().ResetDefaults();
+			Assert.IsNull(req.Settings.JsonSerializer);
+			Assert.IsFalse(req.Settings.Redirects.Enabled);
+			Assert.IsNotNull(req.Settings.BeforeCall);
+			Assert.AreEqual(5, req.Settings.Redirects.MaxAutoRedirects);
 
-			Assert.That(GetSettings().JsonSerializer is DefaultJsonSerializer);
-			Assert.IsTrue(GetSettings().Redirects.Enabled);
-			Assert.IsNull(GetSettings().BeforeCall);
-			Assert.AreEqual(10, GetSettings().Redirects.MaxAutoRedirects);
+			c.Settings.ResetDefaults();
+			req = GetRequest(c);
+
+			Assert.That(req.Settings.JsonSerializer is DefaultJsonSerializer);
+			Assert.IsTrue(req.Settings.Redirects.Enabled);
+			Assert.IsNull(req.Settings.BeforeCall);
+			Assert.AreEqual(10, req.Settings.Redirects.MaxAutoRedirects);
 		}
 
 		[Test] // #256
@@ -160,21 +172,110 @@ public async Task explicit_content_type_header_is_not_overridden() {
 			Assert.AreEqual(new[] { "application/json-patch+json; utf-8" }, h.GetValues("Content-Type"));
 			Assert.AreEqual(new[] { "10" }, h.GetValues("Content-Length"));
 		}
+
+		[Test]
+		public void can_set_timeout() {
+			var c = CreateContainer().WithTimeout(TimeSpan.FromSeconds(15));
+			var req = GetRequest(c);
+			Assert.AreEqual(TimeSpan.FromSeconds(15), req.Settings.Timeout);
+		}
+
+		[Test]
+		public void can_set_timeout_in_seconds() {
+			var c = CreateContainer().WithTimeout(15);
+			var req = GetRequest(c);
+			Assert.AreEqual(req.Settings.Timeout, TimeSpan.FromSeconds(15));
+		}
+
+		[Test]
+		public async Task can_allow_specific_http_status() {
+			using var test = new HttpTest();
+			test.RespondWith("Nothing to see here", 404);
+			var c = CreateContainer().AllowHttpStatus(HttpStatusCode.Conflict, HttpStatusCode.NotFound);
+			await GetRequest(c).DeleteAsync(); // no exception = pass
+		}
+
+		[Test]
+		public async Task allow_specific_http_status_also_allows_2xx() {
+			using var test = new HttpTest();
+			test.RespondWith("I'm just an innocent 2xx, I should never fail!", 201);
+			var c = CreateContainer().AllowHttpStatus(HttpStatusCode.Conflict, HttpStatusCode.NotFound);
+			await GetRequest(c).GetAsync(); // no exception = pass
+		}
+
+		[Test]
+		public void can_clear_non_success_status() {
+			using var test = new HttpTest();
+			test.RespondWith("I'm a teapot", 418);
+			// allow 4xx
+			var c = CreateContainer().AllowHttpStatus("4xx");
+			// but then disallow it
+			c.Settings.AllowedHttpStatusRange = null;
+			Assert.ThrowsAsync<FlurlHttpException>(async () => await GetRequest(c).GetAsync());
+		}
+
+		[Test]
+		public async Task can_allow_any_http_status() {
+			using var test = new HttpTest();
+			test.RespondWith("epic fail", 500);
+			try {
+				var c = CreateContainer().AllowAnyHttpStatus();
+				var result = await GetRequest(c).GetAsync();
+				Assert.AreEqual(500, result.StatusCode);
+			}
+			catch (Exception) {
+				Assert.Fail("Exception should not have been thrown.");
+			}
+		}
 	}
 
 	[TestFixture]
-	public class HttpTestSettingsTests : SettingsTestsBase
+	public class RequestSettingsTests : SettingsTestsBase<IFlurlRequest>
 	{
-		private HttpTest _test;
+		protected override IFlurlRequest CreateContainer() => new FlurlRequest("http://api.com");
+		protected override IFlurlRequest GetRequest(IFlurlRequest req) => req;
 
-		[SetUp]
-		public void CreateTest() => _test = new HttpTest();
+		[Test]
+		public void request_gets_default_settings_when_no_client() {
+			var req = new FlurlRequest();
+			Assert.IsNull(req.Client);
+			Assert.IsNull(req.Url);
+			Assert.IsInstanceOf<DefaultJsonSerializer>(req.Settings.JsonSerializer);
+		}
 
-		[TearDown]
-		public void DisposeTest() => _test.Dispose();
+		[Test]
+		public void can_override_settings_fluently() {
+			using var test = new HttpTest();
+			var cli = new FlurlClient().WithSettings(s => s.AllowedHttpStatusRange = "*");
+			test.RespondWith("epic fail", 500);
+			var req = "http://www.api.com".WithSettings(c => c.AllowedHttpStatusRange = "2xx");
+			req.Client = cli; // client-level settings shouldn't win
+			Assert.ThrowsAsync<FlurlHttpException>(async () => await req.GetAsync());
+		}
+	}
 
-		protected override FlurlHttpSettings GetSettings() => HttpTest.Current.Settings;
-		protected override IFlurlRequest GetRequest() => new FlurlRequest("http://api.com");
+	[TestFixture]
+	public class ClientSettingsTests : SettingsTestsBase<IFlurlClient>
+	{
+		protected override IFlurlClient CreateContainer() => new FlurlClient();
+		protected override IFlurlRequest GetRequest(IFlurlClient cli) => cli.Request("http://api.com");
+	}
+
+	[TestFixture]
+	public class ClientBuilderSettingsTests : SettingsTestsBase<IFlurlClientBuilder>
+	{
+		protected override IFlurlClientBuilder CreateContainer() => new FlurlClientBuilder();
+		protected override IFlurlRequest GetRequest(IFlurlClientBuilder builder) => builder.Build().Request("http://api.com");
+	}
+
+	[TestFixture]
+	public class HttpTestSettingsTests : SettingsTestsBase<HttpTest>
+	{
+		protected override HttpTest CreateContainer() => HttpTest.Current ?? new HttpTest();
+		protected override IFlurlRequest GetRequest(HttpTest container) => new FlurlRequest("http://api.com");
+
+		[TearDown]
+		public void DisposeTest() => HttpTest.Current?.Dispose();
 
 		[Test] // #246
 		public void test_settings_dont_override_request_settings_when_not_set_explicitily() {
@@ -201,30 +302,4 @@ private class FakeSerializer : ISerializer
 			public T Deserialize<T>(Stream stream) => default;
 		}
 	}
-
-	[TestFixture]
-	public class ClientSettingsTests : SettingsTestsBase
-	{
-		private readonly Lazy<IFlurlClient> _client = new Lazy<IFlurlClient>(() => new FlurlClient());
-
-		protected override FlurlHttpSettings GetSettings() => _client.Value.Settings;
-		protected override IFlurlRequest GetRequest() => _client.Value.Request("http://api.com");
-	}
-
-	[TestFixture]
-	public class RequestSettingsTests : SettingsTestsBase
-	{
-		private readonly Lazy<IFlurlRequest> _req = new Lazy<IFlurlRequest>(() => new FlurlRequest("http://api.com"));
-
-		protected override FlurlHttpSettings GetSettings() => _req.Value.Settings;
-		protected override IFlurlRequest GetRequest() => _req.Value;
-
-		[Test]
-		public void request_gets_default_settings_when_no_client() {
-			var req = new FlurlRequest();
-			Assert.IsNull(req.Client);
-			Assert.IsNull(req.Url);
-			Assert.IsInstanceOf<DefaultJsonSerializer>(req.Settings.JsonSerializer);
-		}
-	}
 }