I've put sound deadener on the trunk lid, under the rear deck and, on top of the metal part of the rear deck. I don't have a metal rattling. I have that carpeted plastic deck cover that is rattling. I know that is the culprit because I took it off and put everything else back together and I'm not hearing it as of right now. This is a regal so I'm not completely sure if it is different from a gp but I would think it would be the same. Any ideas on how to get this damn thing to stop rattling? I thought about buying a bag of insulation and putting it between the deck cover and the deck. The problem seems to be that there is a gap between the cover and the deck itself so the cover is just kind of hanging there. So it moves easily with the bass.
