I have a 2008 gt500 with 2.6 pulley,offroad xpipe, intake, and a tune that came with the kit already loaded on the sct tuner. Ive had this setup for over two years with no problems. So I had to take my car in for emissions testing in Illinois and theyre equipment was unable to read anything from my car needless to say I failed the test. So when I get home I hooked up my SCT tuner and and tried to read my dtc, but I keep getting the message unable to read DTC's. I returned the car to stock and tried to read them and it worked fine. I then reloaded the custom tune back onto the car again and tried to read the dtc and recieved the unable to read DTC's message. I'm thinking there is something in the tune itself that is stopping me from reading it, but I have no idea.