ranma21
Supporting Vendor
I used to be a fanatic in sound system, I will literally rip the whole interior off of the vehicle and lay sound dampening material all over it. The cheapest and effective I have found up to date is a roofing material that is call PEEL & SEAL. They look and feel the same as dynamat or other sound dampening material. If I remember right, the maerial is almost the same as well. I have tried them and it works great but with the fraction of the cost. A 6x25 inch roll cost about $15.73 at LOWE's, it was $12 3 years ago.Do not waste your money on specific brand sound dampening material, they works the same by adding mass to reduce vibration to the sheet material hence reduce unwanted sound. If you add foam and felt on top of it, you will be riding a death quite vehicle. Hope this help some mudder to save some $$$$ 
6"x25' Roll Self-Stick Aluminum Faced
6"x25' Roll Self-Stick Aluminum Faced