BMW Speaker install
 

Hi! I recently installed powerful speakers and sub in my X5. The rear door rattles at the sound of bass guitar and is very annoying. The sub, I turned down, and is not as bad, but I'd like to install Dynamat Xtreme.

Anybody on this issue? And how much do I need?

Dynamat won't help your rattling. The rattling is likely coming from the door panel rattling on the door or wires rattling on the door panel or the door itself (or both). The best thing to do is to "de-rattle" the interior door wires (i.e. wrapping them in cloth tape) and the door panel itself (i.e. stuffing matting between the door panel and the door).