exhaust

[lonelywolf8588]

I am wanting to redo the exhaust on my '02 SC2 DOHC. It looks like there are three cats and one muffler or two cats and two mufflers. One attached to the exhaust manifold, one at the bottom of the downpipe, one about two foot past, and a muffler at the bumper. Can I just buy a header and just put one high-flow cat on with a performance muffler? Or do I have to have all that restriction?

[sierrap615]

the frist is a precat to control emissions on cold start-up(i don't know what you PCM would do if it disappears). the second is your main cat(required). the third (which should be like 2+feet long) is a resonator(which doesn't really restrict, just gets rid of that raspy noise). the forth is your muffler.

[lonelywolf8588]

I have seen pictures of people running headers without a precat.

[sierrap615]

i think the pre cat was used on 98+ S-series, maybe only on californa cars? or may that was the AIR system. i'm not sure, but since is is a "warm up" cat, and the OBD system requires the engine to be warm and in closed loop to check the cat effectancy. i have a good feeling it would not set a code. legally can it be removed? no. but that hasn't stoped millions in the past.