Sound dampener material behind the rearseat

[NASSTY]

The tar like stuff crumbles off and makes a mess under the back seat.What is a good replacement for that thingy.I would like to find some material that is lighter than the original stuff but still helps cut down on noise inside the car.Any ideas?

 

[Two Lane]

High-end auto stereo shops have very effective insulating mats and materials available.

HTH

 

[NASSTY]

Thanks