--- a/stress-tester/src/main/java/com/passus/st/client/http/extractor/ContentReplacer.java	Thu Jan 18 10:22:53 2018 +0100
+++ b/stress-tester/src/main/java/com/passus/st/client/http/extractor/ContentReplacer.java	Thu Jan 18 10:53:52 2018 +0100
@@ -21,4 +21,6 @@
 
     public CharSequence replace(CharSequence content, CharSequence value) throws IOException;
 
+    public default void setOption(String name, Object value) {
+    }
 }

--- a/stress-tester/src/main/java/com/passus/st/client/http/extractor/PostValueExtractor.java	Thu Jan 18 10:22:53 2018 +0100
+++ b/stress-tester/src/main/java/com/passus/st/client/http/extractor/PostValueExtractor.java	Thu Jan 18 10:53:52 2018 +0100
@@ -17,26 +17,41 @@
 
     private final ByteString fieldName;
 
+    private boolean escape = true;
+
     public PostValueExtractor(CharSequence fieldName) {
         Assert.notNull(fieldName, "fieldName");
         this.fieldName = ByteString.create(fieldName);
     }
 
     @Override
+    public void setOption(String name, Object value) {
+        switch (name) {
+            case "escape":
+                if (Boolean.FALSE.equals(value)) {
+                    escape = false;
+                } else if (Boolean.TRUE.equals(value)) {
+                    escape = true;
+                }
+                break;
+        }
+    }
+
+    @Override
     public void replace(HttpMessage message, CharSequence value) throws IOException {
-        HttpParameters params = helper.decodeFormUrlencoded(message);
+        HttpParameters params = helper.decodeFormUrlencoded(message, escape);
         if (params != null) {
             params.set(fieldName, value);
-            helper.setFormUrlencoded(message, params);
+            helper.setFormUrlencoded(message, params, escape);
         }
     }
 
     @Override
     public CharSequence replace(CharSequence content, CharSequence value) throws IOException {
-        HttpParameters params = helper.decodeFormUrlencoded(content);
+        HttpParameters params = helper.decodeFormUrlencoded(content, escape);
         if (params != null) {
             params.set(fieldName, value);
-            return params.toString();
+            return params.toString(escape);
         }
 
         return null;

--- a/stress-tester/src/test/java/com/passus/st/client/http/extractor/PostValueExtractorTest.java	Thu Jan 18 10:22:53 2018 +0100
+++ b/stress-tester/src/test/java/com/passus/st/client/http/extractor/PostValueExtractorTest.java	Thu Jan 18 10:53:52 2018 +0100
@@ -1,5 +1,10 @@
 package com.passus.st.client.http.extractor;
 
+import com.passus.net.MimeTypes;
+import com.passus.net.http.HttpHeaders;
+import com.passus.net.http.HttpMessageHelper;
+import com.passus.net.http.HttpRequest;
+import com.passus.net.http.HttpRequestBuilder;
 import java.io.IOException;
 import static org.testng.AssertJUnit.*;
 import org.testng.annotations.Test;
@@ -10,14 +15,35 @@
  */
 public class PostValueExtractorTest {
 
-    private static CharSequence replace(String fieldName, String content, String value) throws IOException {
-        return new PostValueExtractor(fieldName).replace(content, value);
+    @Test
+    public void testReplace() throws IOException {
+        String content = "a=value1&b=value2";
+        PostValueExtractor replacer = new PostValueExtractor("b");
+        assertEquals("a=value1&b=newValue2", replacer.replace(content, "newValue2"));
     }
 
     @Test
-    public void testReplace() throws Exception {
-        String content = "a=value1&b=value2";
-        assertEquals("a=value1&b=newValue2", replace("b", content, "newValue2"));
+    public void testReplaceSpecialCharacters() throws IOException {
+        String contentString = "a=%40%26%3D&b=value2";
+        byte[] content = contentString.getBytes();
+        HttpRequest req = HttpRequestBuilder.post("http://www.example.com")
+                .content(content, MimeTypes.APPLICATION_FORM_URLENCODED)
+                .header(HttpHeaders.CONTENT_LENGTH, String.valueOf(content.length))
+                .build();
+        HttpMessageHelper helper = HttpMessageHelper.get();
+
+        PostValueExtractor replacer = new PostValueExtractor("b");
+        String expectedEnc = "a=%40%26%3D&b=%7B%40var%7D";
+        String expectedRaw = "a=%40%26%3D&b={@var}";
+
+        replacer.setOption("escape", true);
+        replacer.replace(req, "{@var}");
+        assertEquals(expectedEnc, helper.contentToString(req));
+        assertEquals(expectedEnc, replacer.replace(contentString, "{@var}"));
+
+        replacer.setOption("escape", false);
+        replacer.replace(req, "{@var}");
+        assertEquals(expectedRaw, helper.contentToString(req));
+        assertEquals(expectedRaw, replacer.replace(contentString, "{@var}"));
     }
-
 }