I have a 98 OBD-II SR20 and I may need to replace my catalytic convertor...I called around a few muffler shops and they are telling me that I need to get one from the dealer, because an aftermarket one wont be compliant! Is that because its not compliant spec-wise and give me an error code, or they are not guaranteed to work and may/may not give me a code? I am going to take a look at the cat when I install my ebay short shifter, and see if its messed up or not. My car has been really sluggish lately, and overheating a little in long trips in stop and go traffic we have here in LA....a couple gearmonkeys I know say its probably my cat. I dont want to have to go to the dealer to get a stock part, if I can get a low flow or mangaflow part for cheaper...help!