Exhaust Question
 

If I purchased a good muffler and header, could I just have the piping done w/o a cat? I know it's illegal, but there's no such thing as smog tests here. I just need to know if the cat aids in making power at all. Thanks.

usually the cat restricts the exhaust, also taking the cat out may make your exhaust sound like a bee can. The cat is not that restrictive maybe like 2-3 hp

Yes, you can physically do it no prob if you don't mind being illegal (BIG fines and/or jail) and the loud sound.

what are you gonna do with your o2 sensor?