No doubt, Dynamat and its competitors are not just gimmicks - shockingly overpriced, but not gimmicks. They stop large flat panels from making their own musical notes, and lessen the intrusion of road noise. All you have to do is close the door on two cars, one treated and one not, and you will hear the difference - smack v. thud. Big impact on car audio quality.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire