Originally Posted by chrischhorn

Either is good. I still wouldn't waste my money getting the stillen headers installed but if you really want them on. You definitely won't get a big power boost with the OEM cats on but good gawd, with headers and exhaust it does sound sexy!. Right now until my test pipes come in, I'm running Momentum headers, 350z OEM cats, and CNT exhaust and it sounds AMAZING! Real nice smooth and crisp exhaust sound. ZERO rasp since the OEM cats keep it from rasping but as mentioned, it is a power bottle neck. I'll post a sound clip later of how my exhaust sounds for now. I'm kinda sad it won't sound this smooth after the test pipes come in lol.