When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It's just louder and opens up the exhaust more. Stock midpipe on 03 -04 has 4 cats. Change the catback as well because that oem catback is way too restrictive.
itll be noticably louder, and maybe pull a little better in the higher rpms, and do change out the stock catback like lsustang04 said. that would help some too