Originally Posted by Focus7081
Stock is 32-35. So its at least better? On the average. Of course depends on the lead foot driving.
Like Tom said it will vary from person to person. Try it and find out. I have intake, header, and exhaust with toms normal 93 octane tune on my 2.3. when I drive nicely I get 35mpg. If I drive hard I get around 30. I was getting up to 38 before I added the header but that maybe because my driving habit changed.