I'm looking to possibly do a few more exhaust modifications and was wondering how far I could go and still pass emissions? What part of the exhaust do I absolutely need to pass an emissions inspection? So far I have had the resonators deleted and am looking into doing more to get a real nice sound. I've been thinking about a Magnaflow cat but I didn't know if I could just delete the main cat altogether... What exhaust mod would you all recommend that will give my SC4 a very nice and loud sound?

 

the "main cat" you speak of isn't really the main cat...

the SC400's have two main cats, one in each downpipe, just off the exhaust manifold on each side... the one in the middle is just there to help out... it is not monitored and helps in exhaust emissions, but is not primary...

our cars are extremely clean as they stand, to date, my car is the cleaned obd-1 car our shop has ever tested, with HC showing at 1 ppm at idle, and 0 at 2500 rpm, with 0.01% CO output...

no matter what you do to the exhaust, it will have no effect on emissions, so long as you don't screw with the cats... what I plan on doing sometime soon, hopefully, is this:

delete main cats from downpipe area, build a custom Y-pipe that goes into a single, nominally sized aftermarket cat... mount the downstream O2 sensors after this cat (extend wires)... that should be good enough to pass most areas sniffer test...