I have an 04 GTI VR6 had an aftermarket stereo, amp, and subwoofer. For some reason when I pull my key out the subwoofers get back fed and boom once and I can not seem to figure out why. I used the C2R-VW2 interface and installed everything myself being I used to work as an install tech before becoming a mechanic. I've tried everything I can think of and can't figure it out please help me .