I've finally after eight or so years put a head unit in my GTT. But now I've got a really annoying high pitch noise.
I've traced it back to the wideband gauge. Since then I've re wired the stereo and the gauge all the aem wires are in the engine bay with there own power and earth. I'm going to try a different head unit soon.
Anyone got any other suggestions as its driving crazier than I normally am.