diff --git a/aws/rust-runtime/Cargo.lock b/aws/rust-runtime/Cargo.lock
index 20cf7e15df..b94f091e46 100644
--- a/aws/rust-runtime/Cargo.lock
+++ b/aws/rust-runtime/Cargo.lock
@@ -301,7 +301,7 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-runtime"
-version = "1.6.2"
+version = "1.6.3"
 dependencies = [
  "aws-smithy-async",
  "aws-smithy-http",
@@ -326,7 +326,7 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-runtime-api"
-version = "1.7.1"
+version = "1.7.2"
 dependencies = [
  "aws-smithy-async",
  "aws-smithy-types",
diff --git a/aws/sdk/integration-tests/codecatalyst/tests/sso_bearer_auth.rs b/aws/sdk/integration-tests/codecatalyst/tests/sso_bearer_auth.rs
index 99b2b24812..b11861b555 100644
--- a/aws/sdk/integration-tests/codecatalyst/tests/sso_bearer_auth.rs
+++ b/aws/sdk/integration-tests/codecatalyst/tests/sso_bearer_auth.rs
@@ -27,5 +27,5 @@ async fn sso_bearer_auth() {
     let item = &response.items.unwrap()[0];
     assert_eq!("somespacename", item.name);
 
-    replay.full_validate("application/json").await.unwrap();
+    replay.relaxed_validate("application/json").await.unwrap();
 }
diff --git a/aws/sdk/integration-tests/kms/tests/integration.rs b/aws/sdk/integration-tests/kms/tests/integration.rs
index ed534f61bd..7f832bc9e9 100644
--- a/aws/sdk/integration-tests/kms/tests/integration.rs
+++ b/aws/sdk/integration-tests/kms/tests/integration.rs
@@ -8,7 +8,6 @@ use aws_sdk_kms::operation::RequestId;
 use aws_smithy_runtime::client::http::test_util::{ReplayEvent, StaticReplayClient};
 use aws_smithy_runtime_api::client::result::SdkError;
 use aws_smithy_types::body::SdkBody;
-use http::header::AUTHORIZATION;
 use http::Uri;
 use kms::config::{Config, Credentials, Region};
 
@@ -90,7 +89,7 @@ async fn generate_random() {
             .sum::<u32>(),
         8562
     );
-    http_client.assert_requests_match(&[]);
+    http_client.relaxed_requests_match();
 }
 
 #[tokio::test]
@@ -166,5 +165,5 @@ async fn generate_random_keystore_not_found() {
         inner.request_id(),
         Some("bfe81a0a-9a08-4e71-9910-cdb5ab6ea3b6")
     );
-    http_client.assert_requests_match(&[AUTHORIZATION.as_str()]);
+    http_client.relaxed_requests_match();
 }
diff --git a/aws/sdk/integration-tests/qldbsession/tests/integration.rs b/aws/sdk/integration-tests/qldbsession/tests/integration.rs
index 6cdb32d1f1..b0df9190ae 100644
--- a/aws/sdk/integration-tests/qldbsession/tests/integration.rs
+++ b/aws/sdk/integration-tests/qldbsession/tests/integration.rs
@@ -55,5 +55,5 @@ async fn signv4_use_correct_service_name() {
         .await
         .expect("request should succeed");
 
-    http_client.assert_requests_match(&[]);
+    http_client.assert_requests_match(&["authorization"]);
 }
diff --git a/aws/sdk/integration-tests/s3/tests/checksums.rs b/aws/sdk/integration-tests/s3/tests/checksums.rs
index 175f7c5f0f..695b141b83 100644
--- a/aws/sdk/integration-tests/s3/tests/checksums.rs
+++ b/aws/sdk/integration-tests/s3/tests/checksums.rs
@@ -96,7 +96,11 @@ async fn test_checksum_on_streaming_response(
         .await
         .unwrap();
 
-    http_client.assert_requests_match(&["x-amz-checksum-mode", AUTHORIZATION.as_str()]);
+    http_client.assert_requests_match(&[
+        "x-amz-checksum-mode",
+        "x-amz-user-agent",
+        AUTHORIZATION.as_str(),
+    ]);
 
     res
 }
diff --git a/aws/sdk/integration-tests/s3/tests/content-length-enforcement.rs b/aws/sdk/integration-tests/s3/tests/content-length-enforcement.rs
index 3518e8b116..15bc78b276 100644
--- a/aws/sdk/integration-tests/s3/tests/content-length-enforcement.rs
+++ b/aws/sdk/integration-tests/s3/tests/content-length-enforcement.rs
@@ -25,9 +25,10 @@ async fn test_content_length_enforcement_is_not_applied_to_head_request() {
         .await
         .expect("content length enforcement must not apply to HEAD requests");
 
-    // The body returned will be empty, so we pass an empty string to full_validate.
-    // That way, it'll do a string equality check on the empty strings.
-    http_client.full_validate("").await.unwrap();
+    // The body returned will be empty, so we pass an empty string for `media_type` to
+    // `validate_body_and_headers_except`. That way, it'll do a string equality check on the empty
+    // strings.
+    http_client.relaxed_validate("").await.unwrap();
 }
 
 #[tokio::test]
@@ -57,7 +58,10 @@ async fn test_content_length_enforcement_get_request_short() {
     // This will fail with a content-length mismatch error.
     let content_length_err = output.body.collect().await.unwrap_err();
 
-    http_client.full_validate("application/text").await.unwrap();
+    http_client
+        .relaxed_validate("application/text")
+        .await
+        .unwrap();
     assert_eq!(
         DisplayErrorContext(content_length_err).to_string(),
         "streaming error: Invalid Content-Length: Expected 9999 bytes but 10000 bytes were received (Error { kind: StreamingError(ContentLengthError { expected: 9999, received: 10000 }) })"
@@ -91,7 +95,10 @@ async fn test_content_length_enforcement_get_request_long() {
     // This will fail with a content-length mismatch error.
     let content_length_err = output.body.collect().await.unwrap_err();
 
-    http_client.full_validate("application/text").await.unwrap();
+    http_client
+        .relaxed_validate("application/text")
+        .await
+        .unwrap();
     assert_eq!(
         DisplayErrorContext(content_length_err).to_string(),
         "streaming error: Invalid Content-Length: Expected 10001 bytes but 10000 bytes were received (Error { kind: StreamingError(ContentLengthError { expected: 10001, received: 10000 }) })"
diff --git a/aws/sdk/integration-tests/s3/tests/ignore-invalid-xml-body-root.rs b/aws/sdk/integration-tests/s3/tests/ignore-invalid-xml-body-root.rs
index 89b15ba58c..1ab6a6ee5d 100644
--- a/aws/sdk/integration-tests/s3/tests/ignore-invalid-xml-body-root.rs
+++ b/aws/sdk/integration-tests/s3/tests/ignore-invalid-xml-body-root.rs
@@ -10,7 +10,6 @@ use aws_sdk_s3::Config;
 use aws_sdk_s3::{config::Credentials, config::Region, types::ObjectAttributes, Client};
 use aws_smithy_runtime::client::http::test_util::{ReplayEvent, StaticReplayClient};
 use aws_smithy_types::body::SdkBody;
-use http::header::AUTHORIZATION;
 
 const RESPONSE_BODY_XML: &[u8] = b"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<GetObjectAttributesResponse xmlns=\"http://s3.amazonaws.com/doc/2006-03-01/\"><Checksum><ChecksumSHA1>e1AsOh9IyGCa4hLN+2Od7jlnP14=</ChecksumSHA1></Checksum></GetObjectAttributesResponse>";
 
@@ -60,5 +59,5 @@ async fn ignore_invalid_xml_body_root() {
         .await
         .unwrap();
 
-    http_client.assert_requests_match(&[AUTHORIZATION.as_str()]);
+    http_client.relaxed_requests_match();
 }
diff --git a/aws/sdk/integration-tests/s3/tests/naughty-string-metadata.rs b/aws/sdk/integration-tests/s3/tests/naughty-string-metadata.rs
index 3b6bd97002..22d09d1b1f 100644
--- a/aws/sdk/integration-tests/s3/tests/naughty-string-metadata.rs
+++ b/aws/sdk/integration-tests/s3/tests/naughty-string-metadata.rs
@@ -79,20 +79,10 @@ async fn test_s3_signer_with_naughty_string_metadata() {
 
     let _ = builder.send().await.unwrap();
 
+    // As long as a request can be extracted and the `Authorization` header exits, we're good.
+    // We cannot compare a signature in the `Authorization` header between expected and actual
+    // because the signature is subject to change as we update the `x-amz-user-agent` header, e.g.
+    // due to the introduction of a new metric.
     let expected_req = rcvr.expect_request();
-    let auth_header = expected_req
-        .headers()
-        .get("Authorization")
-        .unwrap()
-        .to_owned();
-
-    // This is a snapshot test taken from a known working test result
-    let snapshot_signature =
-        "Signature=a5115604df66219874a9e5a8eab4c9f7a28c992ab2d918037a285756c019f3b2";
-    assert!(
-        auth_header .contains(snapshot_signature),
-        "authorization header signature did not match expected signature: got {}, expected it to contain {}",
-        auth_header,
-        snapshot_signature
-    );
+    let _ = expected_req.headers().get("Authorization").unwrap();
 }
diff --git a/aws/sdk/integration-tests/s3/tests/no_auth.rs b/aws/sdk/integration-tests/s3/tests/no_auth.rs
index 170332d00d..644e05addc 100644
--- a/aws/sdk/integration-tests/s3/tests/no_auth.rs
+++ b/aws/sdk/integration-tests/s3/tests/no_auth.rs
@@ -33,7 +33,7 @@ async fn list_objects() {
     dbg!(result).expect("success");
 
     http_client
-        .validate_body_and_headers(None, "application/xml")
+        .relaxed_validate("application/xml")
         .await
         .unwrap();
 }
@@ -65,7 +65,7 @@ async fn list_objects_v2() {
     dbg!(result).expect("success");
 
     http_client
-        .validate_body_and_headers(None, "application/xml")
+        .relaxed_validate("application/xml")
         .await
         .unwrap();
 }
@@ -96,7 +96,7 @@ async fn head_object() {
     dbg!(result).expect("success");
 
     http_client
-        .validate_body_and_headers(None, "application/xml")
+        .relaxed_validate("application/xml")
         .await
         .unwrap();
 }
@@ -127,7 +127,7 @@ async fn get_object() {
     dbg!(result).expect("success");
 
     http_client
-        .validate_body_and_headers(None, "application/xml")
+        .relaxed_validate("application/xml")
         .await
         .unwrap();
 }
diff --git a/aws/sdk/integration-tests/s3/tests/normalize-uri-path.rs b/aws/sdk/integration-tests/s3/tests/normalize-uri-path.rs
index 11ee0f7b09..135fb35df8 100644
--- a/aws/sdk/integration-tests/s3/tests/normalize-uri-path.rs
+++ b/aws/sdk/integration-tests/s3/tests/normalize-uri-path.rs
@@ -34,18 +34,7 @@ async fn test_operation_should_not_normalize_uri_path() {
         .unwrap();
 
     let request = rx.expect_request();
-    let actual_auth =
-        std::str::from_utf8(request.headers().get("authorization").unwrap().as_bytes()).unwrap();
-
     let actual_uri = request.uri();
     let expected_uri = "https://test-bucket-ad7c9f01-7f7b-4669-b550-75cc6d4df0f1.s3.us-east-1.amazonaws.com/a/.././b.txt?x-id=PutObject";
-    assert_eq!(actual_uri, expected_uri);
-
-    let expected_sig = "Signature=2ac540538c84dc2616d92fb51d4fc6146ccd9ccc1ee85f518a1a686c5ef97b86";
-    assert!(
-        actual_auth.contains(expected_sig),
-        "authorization header signature did not match expected signature: expected {} but not found in {}",
-        expected_sig,
-        actual_auth,
-    );
+    assert_eq!(expected_uri, actual_uri);
 }
diff --git a/aws/sdk/integration-tests/s3/tests/query-strings-are-correctly-encoded.rs b/aws/sdk/integration-tests/s3/tests/query-strings-are-correctly-encoded.rs
index 53560e3beb..31870702dd 100644
--- a/aws/sdk/integration-tests/s3/tests/query-strings-are-correctly-encoded.rs
+++ b/aws/sdk/integration-tests/s3/tests/query-strings-are-correctly-encoded.rs
@@ -36,23 +36,12 @@ async fn test_s3_signer_query_string_with_all_valid_chars() {
         .send()
         .await;
 
+    // As long as a request can be extracted and the `Authorization` header exits, we're good.
+    // We cannot compare a signature in the `Authorization` header between expected and actual
+    // because the signature is subject to change as we update the `x-amz-user-agent` header, e.g.
+    // due to the introduction of a new metric.
     let expected_req = rcvr.expect_request();
-    let auth_header = expected_req
-        .headers()
-        .get("Authorization")
-        .unwrap()
-        .to_owned();
-
-    // This is a snapshot test taken from a known working test result
-    let snapshot_signature =
-        "Signature=9a931d20606f93fa4e5553602866a9b5ccac2cd42b54ae5a4b17e4614fb443ce";
-    assert!(
-        auth_header
-            .contains(snapshot_signature),
-        "authorization header signature did not match expected signature: got {}, expected it to contain {}",
-        auth_header,
-        snapshot_signature
-    );
+    let _ = expected_req.headers().get("Authorization").unwrap();
 }
 
 // This test can help identify individual characters that break the signing of query strings. This
diff --git a/aws/sdk/integration-tests/s3/tests/request_information_headers.rs b/aws/sdk/integration-tests/s3/tests/request_information_headers.rs
index 47de27c437..c444aa5b88 100644
--- a/aws/sdk/integration-tests/s3/tests/request_information_headers.rs
+++ b/aws/sdk/integration-tests/s3/tests/request_information_headers.rs
@@ -103,11 +103,13 @@ async fn three_retries_and_then_success() {
     let resp = resp.expect("valid e2e test");
     assert_eq!(resp.name(), Some("test-bucket"));
     http_client
-        .full_validate("application/xml")
+        .relaxed_validate("application/xml")
         .await
-        .expect("failed")
+        .unwrap();
 }
-//
+
+// TODO(simulate time): Currently commented out since the test is work in progress.
+//  Consider using `tick_advance_time_and_sleep` to simulate client and server times.
 // // # Client makes 3 separate SDK operation invocations
 // // # All succeed on first attempt.
 // // # Fast network, latency + server time is less than one second.
@@ -190,7 +192,9 @@ async fn three_retries_and_then_success() {
 //     assert_eq!(resp.name(), Some("test-bucket"));
 //     conn.full_validate(MediaType::Xml).await.expect("failed")
 // }
-//
+
+// TODO(simulate time): Currently commented out since the test is work in progress.
+//  Consider using `tick_advance_time_and_sleep` to simulate client and server times.
 // // # One SDK operation invocation.
 // // # Client retries 3 times, successful response on 3rd attempt.
 // // # Slow network, one way latency is 2 seconds.
diff --git a/aws/sdk/integration-tests/s3/tests/signing-it.rs b/aws/sdk/integration-tests/s3/tests/signing-it.rs
index 450f4ba43f..08f1cc29d8 100644
--- a/aws/sdk/integration-tests/s3/tests/signing-it.rs
+++ b/aws/sdk/integration-tests/s3/tests/signing-it.rs
@@ -10,6 +10,7 @@ use aws_sdk_s3::config::{Credentials, Region};
 use aws_sdk_s3::{Client, Config};
 use aws_smithy_runtime::client::http::test_util::{ReplayEvent, StaticReplayClient};
 use aws_smithy_types::body::SdkBody;
+use http::header::AUTHORIZATION;
 
 #[tokio::test]
 async fn test_signer() {
@@ -37,5 +38,5 @@ async fn test_signer() {
         .send()
         .await;
 
-    http_client.assert_requests_match(&[]);
+    http_client.assert_requests_match(&[AUTHORIZATION.as_str()]);
 }
diff --git a/aws/sdk/integration-tests/s3control/tests/signing-it.rs b/aws/sdk/integration-tests/s3control/tests/signing-it.rs
index 6d258496b1..b235f7aa1d 100644
--- a/aws/sdk/integration-tests/s3control/tests/signing-it.rs
+++ b/aws/sdk/integration-tests/s3control/tests/signing-it.rs
@@ -8,6 +8,7 @@ use aws_sdk_s3control::config::{Credentials, Region};
 use aws_sdk_s3control::{Client, Config};
 use aws_smithy_runtime::client::http::test_util::{ReplayEvent, StaticReplayClient};
 use aws_smithy_types::body::SdkBody;
+use http::header::AUTHORIZATION;
 
 #[tokio::test]
 async fn test_signer() {
@@ -39,5 +40,5 @@ async fn test_signer() {
         .await
         .expect_err("empty response");
 
-    http_client.assert_requests_match(&[]);
+    http_client.assert_requests_match(&[AUTHORIZATION.as_str()]);
 }
diff --git a/rust-runtime/Cargo.lock b/rust-runtime/Cargo.lock
index b0711de2a3..aa7db1e7f1 100644
--- a/rust-runtime/Cargo.lock
+++ b/rust-runtime/Cargo.lock
@@ -304,7 +304,7 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-cbor"
-version = "0.60.6"
+version = "0.60.7"
 dependencies = [
  "aws-smithy-types 1.2.1",
  "criterion",
@@ -363,7 +363,7 @@ version = "0.60.3"
 name = "aws-smithy-compression"
 version = "0.0.1"
 dependencies = [
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "bytes",
  "bytes-utils",
@@ -407,8 +407,8 @@ name = "aws-smithy-experimental"
 version = "0.1.3"
 dependencies = [
  "aws-smithy-async 1.2.1",
- "aws-smithy-runtime 1.6.2",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime 1.6.3",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "h2 0.4.5",
  "http 1.1.0",
@@ -450,7 +450,7 @@ version = "0.60.9"
 dependencies = [
  "async-stream",
  "aws-smithy-eventstream 0.60.4",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "bytes",
  "bytes-utils",
@@ -479,7 +479,7 @@ dependencies = [
  "aws-smithy-cbor",
  "aws-smithy-http 0.60.9",
  "aws-smithy-json 0.60.7",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "aws-smithy-xml 0.60.8",
  "bytes",
@@ -569,7 +569,7 @@ name = "aws-smithy-mocks-experimental"
 version = "0.2.1"
 dependencies = [
  "aws-sdk-s3",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "tokio",
 ]
@@ -595,7 +595,7 @@ name = "aws-smithy-protocol-test"
 version = "0.62.0"
 dependencies = [
  "assert-json-diff",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "base64-simd",
  "cbor-diag",
  "http 0.2.12",
@@ -648,13 +648,13 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-runtime"
-version = "1.6.2"
+version = "1.6.3"
 dependencies = [
  "approx",
  "aws-smithy-async 1.2.1",
  "aws-smithy-http 0.60.9",
  "aws-smithy-protocol-test 0.62.0",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "bytes",
  "fastrand",
@@ -700,7 +700,7 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-runtime-api"
-version = "1.7.1"
+version = "1.7.2"
 dependencies = [
  "aws-smithy-async 1.2.1",
  "aws-smithy-types 1.2.1",
@@ -790,7 +790,7 @@ name = "aws-smithy-wasm"
 version = "0.1.3"
 dependencies = [
  "aws-smithy-http 0.60.9",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "bytes",
  "http 1.1.0",
@@ -1975,10 +1975,11 @@ checksum = "bfa799dd5ed20a7e349f3b4639aa80d74549c81716d9ec4f994c9b5815598306"
 name = "inlineable"
 version = "0.1.0"
 dependencies = [
+ "aws-smithy-cbor",
  "aws-smithy-compression",
  "aws-smithy-http 0.60.9",
  "aws-smithy-json 0.60.7",
- "aws-smithy-runtime-api 1.7.1",
+ "aws-smithy-runtime-api 1.7.2",
  "aws-smithy-types 1.2.1",
  "aws-smithy-xml 0.60.8",
  "bytes",
diff --git a/rust-runtime/aws-smithy-runtime/Cargo.toml b/rust-runtime/aws-smithy-runtime/Cargo.toml
index 0235893492..1a2d2adf42 100644
--- a/rust-runtime/aws-smithy-runtime/Cargo.toml
+++ b/rust-runtime/aws-smithy-runtime/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "aws-smithy-runtime"
-version = "1.6.2"
+version = "1.6.3"
 authors = ["AWS Rust SDK Team <aws-sdk-rust@amazon.com>", "Zelda Hessler <zhessler@amazon.com>"]
 description = "The new smithy runtime crate"
 edition = "2021"
diff --git a/rust-runtime/aws-smithy-runtime/src/client/http/test_util/dvr/replay.rs b/rust-runtime/aws-smithy-runtime/src/client/http/test_util/dvr/replay.rs
index ada8a4befb..e4ad46494a 100644
--- a/rust-runtime/aws-smithy-runtime/src/client/http/test_util/dvr/replay.rs
+++ b/rust-runtime/aws-smithy-runtime/src/client/http/test_util/dvr/replay.rs
@@ -4,6 +4,7 @@
  */
 
 use super::{Action, ConnectionId, Direction, Event, NetworkTraffic};
+use crate::client::http::test_util::replay::DEFAULT_RELAXED_HEADERS;
 use aws_smithy_protocol_test::MediaType;
 use aws_smithy_runtime_api::client::connector_metadata::ConnectorMetadata;
 use aws_smithy_runtime_api::client::http::{
@@ -68,6 +69,11 @@ impl fmt::Debug for ReplayingClient {
     }
 }
 
+enum HeadersToCheck<'a> {
+    Include(&'a [&'a str]),
+    Exclude(Option<&'a [&'a str]>),
+}
+
 impl ReplayingClient {
     fn next_id(&self) -> ConnectionId {
         ConnectionId(self.num_events.fetch_add(1, Ordering::Relaxed))
@@ -78,25 +84,60 @@ impl ReplayingClient {
         self.validate_body_and_headers(None, media_type).await
     }
 
+    /// Convenience method to validate that the bodies match, using a given [`MediaType`] for
+    /// comparison, and that the headers are also match excluding the default relaxed headers
+    ///
+    /// The current default relaxed headers:
+    /// - x-amz-user-agent
+    /// - authorization
+    pub async fn relaxed_validate(self, media_type: &str) -> Result<(), Box<dyn Error>> {
+        self.validate_body_and_headers_except(DEFAULT_RELAXED_HEADERS, media_type)
+            .await
+    }
+
     /// Validate actual requests against expected requests
     pub async fn validate(
         self,
         checked_headers: &[&str],
         body_comparer: impl Fn(&[u8], &[u8]) -> Result<(), Box<dyn Error>>,
     ) -> Result<(), Box<dyn Error>> {
-        self.validate_base(Some(checked_headers), body_comparer)
+        self.validate_base(HeadersToCheck::Include(checked_headers), body_comparer)
             .await
     }
 
     /// Validate that the bodies match, using a given [`MediaType`] for comparison
     ///
-    /// The specified headers are also validated
+    /// The specified headers are also validated. If `checked_headers` is a `None`, it means
+    /// checking all headers.
     pub async fn validate_body_and_headers(
         self,
         checked_headers: Option<&[&str]>,
         media_type: &str,
     ) -> Result<(), Box<dyn Error>> {
-        self.validate_base(checked_headers, |b1, b2| {
+        let headers_to_check = match checked_headers {
+            Some(headers) => HeadersToCheck::Include(headers),
+            None => HeadersToCheck::Exclude(None),
+        };
+        self.validate_base(headers_to_check, |b1, b2| {
+            aws_smithy_protocol_test::validate_body(
+                b1,
+                std::str::from_utf8(b2).unwrap(),
+                MediaType::from(media_type),
+            )
+            .map_err(|e| Box::new(e) as _)
+        })
+        .await
+    }
+
+    /// Validate that the bodies match, using a given [`MediaType`] for comparison
+    ///
+    /// The headers are also validated unless listed in `excluded_headers`
+    pub async fn validate_body_and_headers_except(
+        self,
+        excluded_headers: &[&str],
+        media_type: &str,
+    ) -> Result<(), Box<dyn Error>> {
+        self.validate_base(HeadersToCheck::Exclude(Some(excluded_headers)), |b1, b2| {
             aws_smithy_protocol_test::validate_body(
                 b1,
                 std::str::from_utf8(b2).unwrap(),
@@ -109,7 +150,7 @@ impl ReplayingClient {
 
     async fn validate_base(
         self,
-        checked_headers: Option<&[&str]>,
+        checked_headers: HeadersToCheck<'_>,
         body_comparer: impl Fn(&[u8], &[u8]) -> Result<(), Box<dyn Error>>,
     ) -> Result<(), Box<dyn Error>> {
         let mut actual_requests =
@@ -133,8 +174,11 @@ impl ReplayingClient {
                 .keys()
                 .map(|k| k.as_str())
                 .filter(|k| match checked_headers {
-                    Some(list) => list.contains(k),
-                    None => true,
+                    HeadersToCheck::Include(headers) => headers.contains(k),
+                    HeadersToCheck::Exclude(excluded) => match excluded {
+                        Some(headers) => !headers.contains(k),
+                        None => true,
+                    },
                 })
                 .flat_map(|key| {
                     let _ = expected.headers().get(key)?;
diff --git a/rust-runtime/aws-smithy-runtime/src/client/http/test_util/replay.rs b/rust-runtime/aws-smithy-runtime/src/client/http/test_util/replay.rs
index b47bedfac0..adbd5aa5bf 100644
--- a/rust-runtime/aws-smithy-runtime/src/client/http/test_util/replay.rs
+++ b/rust-runtime/aws-smithy-runtime/src/client/http/test_util/replay.rs
@@ -18,6 +18,8 @@ use std::sync::{Arc, Mutex, MutexGuard};
 
 type ReplayEvents = Vec<ReplayEvent>;
 
+pub(crate) const DEFAULT_RELAXED_HEADERS: &[&str] = &["x-amz-user-agent", "authorization"];
+
 /// Test data for the [`StaticReplayClient`].
 ///
 /// Each `ReplayEvent` represents one HTTP request and response
@@ -230,6 +232,17 @@ impl StaticReplayClient {
             self.requests().len()
         );
     }
+
+    /// Convenience method for `assert_requests_match` that excludes the pre-defined headers to
+    /// be ignored
+    ///
+    /// The pre-defined headers to be ignored:
+    /// - x-amz-user-agent
+    /// - authorization
+    #[track_caller]
+    pub fn relaxed_requests_match(&self) {
+        self.assert_requests_match(DEFAULT_RELAXED_HEADERS)
+    }
 }
 
 impl HttpConnector for StaticReplayClient {