Ok I just ordered a xcal 2 for my 99gt. I plugged it into my diagnostics port and it would not power up, tried it on my friends gt same thing. But I plug it into my usb port on laptop and it powers up but when i try to tune it it says voltage to low try agian. Is it a bad tuner or and i missing somthing? Any one with any comments I would apprciate it thanks.