I have recently installed a pioneer DEH-4300UB headunit and replaced all the speakers in my car. They have ben fine for a couple of months now. I removed the roof lining the other day because it was sagging and since then when i turn my stereo up above 30 it makes the sort of noise you would get from two speaker wires touching. Today i have pulled the stereo out and checked all the wiring and all of the speakers and tried another stereo but its still the same. Does anyone have any idea what could be causing this?