95DB in california, I got reffed, I know, passed at 92DB with the MSA catback with the "turbo" muffler it comes with. With a cat, also the ticket for modified exhaust is not repairable, so no point of getting it reffed, i jumped through all the hoops just to be told at the courthouse that its not repairable.
As far as exhausts go, anything after the cat is technically legal, as you are not supposed to tamper with any smog devices, cat back is after the smog therefore ok, also as long as its not too loud you'll be fine. that kind of depends on where you are, some cities are more relaxed than others, the city where i live is not as anal about modified cars as the one two exits down where i got pulled over. i suggest get whatever piping you want and get a muffler that doesnt jump out and say look im modified.