And test pipes IMO arent worth it. But dont take my word i do not have first hand experience..im just relaying to you what others on this site have told me. High flow cats flow if not as well, almost as well as test/race pipes. Whatever you wanna call it, either way the trade-off(smell, illegalness) of test pipes arent worth it. Just pick up a nice high-flow cat. Magnaflow, Hytech, idk couple others make great cats.