no it ran perfect before the exhaust. i had no cat no res and no mufflers. no the welded the stuff in the down pipe that was leaking and i have a res. and from the y pipe were it splits to dual's and they put 1.7/8 before i was 3" to 2"1/2 from the cat back. Still have no cat too.

And a buddy of mine that built an 11 sec gtp said i would be able to run this without like cams fine. i just need to get it tuned correctly. ohh and i have the zzp 1.0 and a k/n cold air intake