haha, im in the middle of doing something similar to this. Ive been sound dampening the entire car to get rid of rattling. Since i have a Kicker L7, the back deck lid and the door panels are rattling. So i sound dampened the rear deck lid and im about to polyfill the doors. I want my car to be as quiet as my sister-in-law's 750IL by the time im through.
BTW: I used the factory speaker wire at the radio harness rather than running new speaker wire. The factory wiring is 18ga by the looks of it. It prevents me from having to hack or run wires through the boot.