I have a small sub in my trunk and am getting lots of vibration coming from the plastic panel behind the head rest (where the tops sits when the top is down). If the top is down, there is little or no vibration because the top is pressing against it. Anyone have any ideas on how to stop this. Since winter is coming, I won't be able to ride with the top down and that vibration is going to drive me crazy! Thanks in advance.

 

I cut out the whole inside of the panel, and covered the piece with soft speaker grill cloth. This allowed for more air flow and also eliminated the plastic on plastic rattling.

 

I ended up cramming so much stuff into the spare tire area that Wesmaster's solution wasn't feasible for me. Its the easiest and most efficient solution though. An alternative is to line the seal for the tray with 1/16" neoprene or rubber stripping and then reassemble. Dynomat is too stiff for this project.