Modify Cat's
 

What would happen if i took the stock cat's and put a fairly large hole through them? would i get the effect of test pipes to a certain extent, would the car not smell as bad as it does with test pipes? Thanks

If you gut your cats, it'll be just as good as test pipes, and it'll smell like test pipes too. It might sound raspier too.

It'd be basically the same as test pipes. I personally would just spend the money on test pipes if I were you. If you ever have to go back to 'stock', then you'd have the option. If you hollow out your cats now, you have no way of going back. Test pipes are cheap. Hollowing out cats is a lot of work.

yup, just buy some TPs and save the cats. OEM cats are pretty expensive if you end up hating the smell or need to go OEM for some reason.

i have test pipes on now. my question was really asking if i were to leave part of the element in the cats would i have the partial effect of cats. would it be a bit louder and still have some of the "bad stuff" burnt off by the remaining element?

Well it's "possible" that leaving part of the element would help burn off some bad junk, but the partial cat material may disrupt air flow in a negative way. Just buy high flow cats

I gutted my cat on my old maxima. Sounded like the ricest POS out there.

Gut the cats and you'll get some hellacious resonating and turbulence in the housing. The odd shape of the cat housing will not lend well to keeping up exhaust velocity.