i got a 2.5 exhaust.. from the downpipe all the way back... except... i have a gutted stock cat that i use for racing. now... i believe that i might be bottleneckin with the stock cat...

any proof or solid facts as to how a 2.5 carsound cat would benefit me more than the gutted free flowing cat? cause if i dont really need to spend the money on one.. i rather just keep the gutted cat on.

 

A straight through pipe (test pipe) would provide the best flow. The problems with a gutted cat is that you have a small inlet, then a large chamber, then back to a small outlet... which makes turbulence... which slows the flow.

 

yes get a test pipe, they are only 35 i believe. but it might throw codes at you.

 

yeah, id take that gutted factory cat and cut it apart. cut a piece of 2.5" pipe the size of the large chamber of the cat, and make a bolt-on test pipe, welding the 2 flanges to each end. you can even weld on the O2 threading if your car has one on the cat. youll have much better results, and youre lookin at about 5 bucks, considering you or a friend can weld. also, id recommend spray painting it with 1500 deg. silver or flat black paint, to protect it from rusting.


[Modified by 22lbGS-R, 10:03 PM 1/2/2003]