I have a 04 Comp G with a CAI and 1.9 rockers, and would love to modify the stock exhaust since I can't hear the car at all, so here is my question:

Will installing an offroad downpipe and custom made (wider diameter) exhaust system along with deleting the cats throw the car into limp mode without a tuned PCM? Or will it run without any major issues other than not getting the most power out it?

Thanks for the help