tahoeZ2

A ground loop is your most likely cause. Try moving your grounds, don't use the factory ground and make sure its clean metal (no paint). If that doesn't do it Radio Shack carries Inline filters (noise suppressors)that will magnetically remove any engine noise.

Metra makes an interface for Bose and the Data System, GMOS-4 best buy has em for $120 or so, even gives you your VSS and Reverse wires on the harness, plus a 12V accesorry

Use Monster Cleaner, nothing will give you a better finish, and its make for screens. You can get it at Best buy. a bottle last me 4 months with regular use