Thanks for the responses. I will probably do the 3 inch downpipe/cat assembly both now that you mention it gtpsinc. If the car continues to set a P0420 code isn't that going to screw gas mileage? That code is a result of the emissions computer getting an improper fuel/air mix reading on the exhaust right? Won't that result in the computer leaning the car out or richening it up until it gets the right post combustion mix, or am I being stupid about this?