Quote Originally Posted by Bludsport View Post
Dynamat is not really a "sound deadener", it's a vibration and resonance damping type of material. If you want to deaden sounds like engine, exhaust, road noise, etc., the best solution is to combine a vibration damping material like Dynamat along with a 'decoupled' layer of MLV (mass loaded vinyl). The trick is to not attach the MLV material directly to the sheet metal of the car, but instead apply it to the vibration damping material. I have a convertible and noticed a lot of noise coming from the rear wheel arches, fuel pump and exhaust. It's a pain in the ass, but I recently installed some MLV along with CLD tiles (similar to dynamat) in my trunk and the results were pretty amazing. BMW also used CLD tiles in areas like the front doors and the spare tire area, but not really enough to make a big difference.
Just wanted to add to this discussion as I just did this this weekend.

Agreed. In fact, Dynamat explicitly describes this exact process. While I admit the factory crayon garbage had deteriorated to the point that a trash bag of mashed Ritz crackers stuffed under the seats would've been more effective, the difference was indeed noticeably quieter. It also adds mass and continuity to those panels reducing vibrations.

Stripped of the factory garbage...

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Dynamat and 1/2" Dynaliner applied...

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