newbie in need of advice
 

I'm not real familiar with Mazda. i want do a cat-back and keep it street legal but like i said i don't know shit about Mazda, besides the fact that my 03.5 msp is kick ass.



also does anyone know if a cat-back will burn my o2 sensors out?

No. A catback will only replace the exhaust from AFTER the cat so it should still be street legal. A little louder yes, but emissions will not be affected.

Yeah, pretty much what Fox said, as well, it won't burn any sensors as there are no sensors to burn after the 2nd cat.

RacingBeat's Protege catback is among the best, but most are street legal (unless your area has noise restrictions, then some catbacks may be too loud.)