When I removed my door panels, and have been, to try to deaden the rattles that I have, I noticed that I have a big plastic sheet covering MOST of the door. Is this there normally or did the shop put this on there when installing my system? If its NOT needed, I just might take it off then, cause its causing some vibrations of its own....LOL.

 

Yeah i think that plastic sheet is installed at the factory to keep out water or something

 

factory

 

Yup, factory moisture barrier. I've never personally experienced any problems from removing the plastic. But I don't live in New Orleans or any place where it rains constantly. You can completely cover the door panel and all the holes with damping material to eliminate the need for the plastic sheet.