sound proofing

I was exploring the trunk last night and found a wierd piece that was making the annoying vibration noise. As I was standing at the trunk looking in, I could hear a vibration to the right side, and thanks to GM and their poopty ideas of how to put a car together, I pulled the carpet back and found that a piece of metal that forms the shape of the trunk that extends off the wheel well was vibrating terribly. I dont know how to fix it yet as I will wait till warmer weather, but perhaps this is a big source of vibration outside of the lid? Anyone else notice this? You have to have your subs on and not turned on loud to hear it, maybe 1/4 of max.

Finally a warm day in Indiana! (not really but compared to the negative temps this past weekend we will take it!) I was able to find the source of a nasty rattle in my trunk. If you pull the carpeting back on the right side as you look in at the trunk from the back bumper, there is a vent or something sorta hidden behind the panel that is part of the wheel well. There are a couple of rubber pieces that are supposedly to keep dust and dirt outta the trunk or something. I tore them out, leaving the vent without those rubber pieces and the rattling disappeared, except of course the trunk lid pieces. I am planning on trying to make a setup to reattach the snap on piece on the trunk with bolts and washers, instead of those crappy plastic snaps. As soon as I get a good setup going, I will post what I did. If anyone else has a better idea besides foam let me know!