the vibration from my subs was irratating me beyond belief and i found a cheap solution at Lowes (i am sure you can get it at Home Depot as well)... window/door foam weatherstripping (single side adhesive). i got the 1/2" tall by 1/2" wide one that came in a roll 10' long for ~$3.50. i bought two rolls and now i do not have a hint of ratteling.

i removed the rear deck (as if you were to replace speakers) and applied it and boxed in every "opening" (hole) as well as the ends where the deck met the plastic/carpet piece. then iput the deck back on. after that, i applied it all around the piece that attaches from the front (with the black fake leather stuff that covers the padding) screwed it all together, and now i have no ratteling!

so if the ratteling is getting to you, i HIGHLY recommend doing so. i would have taken pics if i would have known that it worked that well!