I wonder what would happen if...

[jaxvon]

I wonder what would happen if you applied this stuff to the inside of your your speaker cabs along with the normal stuffing. Hmm...

http://www.quietsolution.com/QCar_dsheet_scn.pdf

 

[Francious70]

This is pretty much spray-in truck bed liner. It achieves the same thing as dynomat, or concrete if you really want to deaden sound.

Paul