I have a scion tc and I am about to deaden the back hatch area. most other outer metal panels are deadened already. The hatch is hard because the metal area is actually two layers close together with the top one only having lots of little small holes in it. I can put some foam between the layers but I cant put any deadening material on the outer layer. I was honestly thinking of foaming it, covering the exposed layer and some of the holes with butyl deadening, and then mass loading the plastic that attaches to the metal so that some of sound would reflect more and it would move a bit less (although with probably equal inertia).
I'm wondering if this would be effective or what would for this area? I'm worried that mass loading it would just make it move less but due to the same amount of energy hitting it and it being more massive, it may still shake against the metal with as much noise. I've seen some people just remove the plastic altogether and that helped. Any ideas or experiences are welcome.