Quote Originally Posted by DC2-PWR View Post
Last time I changed a full exhaust on a DC5R the o2 Sensor was plugged in the extractor pipe. So I don't know how you found an o2 sensor on a cat? Are you talking from your own experiance? Sorry just curious.

De-cat does nothing. I had de-cat, no resonator, all on stock headers with Buddyclub spec3 exhaust and it sounded retardedly loud and all I smelt was fume in my cabin. Biggest headahce of an idea and exhaust popped way too much with exessive amount of flames/petrol.

Best thing was when I added a 200cell hi-flow cat, there was a nice difference and car still sounded nice. No fume smell, reduceded popping.
The DC5Rs have a primary and seconday o2 sensor. The primary is in the extractor pipe and the secondary is in the cat. The reason for this is so that the ecu can take a reading both before and inside the cat, to ensure that the cat is doing it's job (to reduce emissions).

I am currently running a de-cat system, however that is because by headers came out of the box as a de-cat item, not because I removed it. The only reason I haven't put one in is because I'm hesitant to cut up a $1200+ header. And even still I'm considering doing it anyway just to be on the safe side.

To the OP, don't remove your cat man. Way more headaches than it's worth. Trust me from experience, a de-cat exhaust on a car with modern sensors and ecu is a nightmare. All for what? A little extra noise?