Sound insulating

Is there a substitute to using products like dynamat for sound insulation, i was maybe thinking foam or other soft material like carpet. My subs are in my trunk and it rattles like crazy when i turn them up. I was also wondering if i turned my subs to face the interior of the car instead of the trunk. BTW i have two twleves in a ported box, and its a nissan sentra. One more question, is there any after market rear view mirror that either moves less with vibrations or doesnt make a rattling sound when bass is played. Thanks

They have spray on deadener, paint on. But for large surface the mat is the best. Go to secondskinaudio.com, cheaper and better than dynamat.

AS for the mirror, good luck on that the one that was in my corolla fell off the bracket, and the one in my blazer moves down every time it hits.

the dynamat type mats work by bonding with the metal or plastic surface you are applying it too, it raises the mass and lowers the resonant frequency. The only two worth a crap are the dynamat extreme and secondskin damplifier, they are butyl based so they don't have the asphalt smell either. Foam is occasionally useful for like putting between the front part of the front door and side of the dash or something like that. You can also try using non-hardening clay from a hobby store.