Questions about performance upgrades

I have a 99 SV. I am interested in replacing the cats with test pipes. I am concerned about this triggering the check engine light and also wondering how much louder the car would be? I also am looking for a NOS kit for the car. Does anyone have experience with a NOS kit? Any advise and information would be appreciated. The car is currently stock with the exception of a Quicksilver bypass muffler (straight pipe replacement).

Thanks

i know allanlambo has a nos kit, and craiglebeman says he has one as well. Im sure they would be able to answer your questions if you ask them nicely