Had my Kinetix high flow cats installed by my exhaust guy, i pretty much supervised the whole install so i didnt see anything that could have damaged the O2 sensors. The neg battery terminal was disconnected before install. It was fine for roughly 35 miles then after some hard driving it flipped on. Ever since the install my exhaust sounds like its been misfiring with small sputters. Overall the car has gained in performance but the idle is kind of rough. Anyone else have this problem?

 

I would double check the header to cat connection to make sure it is not leaking that might cause some running problems, the misfiring like sputter sounds are normal even before any mods, you just probably notice them because you are paying attention to it.

 

yeah, mine sputters sometimes at idle too. (with the factory plenum, too) But I haven't noticed it since I put in NGK Irridiums.