I purchased my GT500 a few weeks ago, and love the hell out of it. The thing is a monster!! But twice now I have taken it to get the emissions tests, and twice it has failed because they don't get a reading from 3 monitors when they plug it in. At first they told me to drive it for 80-100 miles or so to reset the sensors, but I did that and brought it back the 2nd time with the same result. The monitors that are the issue are the Catalyst (CAT), The Oxygen Sensor, and the Heated Oxygen Sensor. The car is definitely not stock (mods in my sig), but unfortunately it didn't come with a tuner. As far as I can tell, there is a catted midpipe in there. Could there be a custom tune that turns off those sensors for some kind of performance gain? Would I need to buy a tuner and a custom tune and replace what's on there? Thanks.