Does anyone have a DIY I can follow to take the rear deck apart? Or at the very least a few pointers to give to an audio shop.

I heard it's a big hassle to take apart but it rattles like crazy when I play music. I'd like to throw some dynamat or foam in it.

 

The rear seat bottom should pull off. No screws just grab the bottom and pull. Then, you will see the 10mm bolts on the sides and center of seat back. Remove bolts and lift up. Seat back should come right off. You should be able to figure out the deck from there.

I don't know if Dynamat will help, due to the gap between the metal and the cover.