Hal, I used a product called FatMat for sound dampening when I remodeled the interior of my coach. It is a butyl product that is has similar performance characteristics to Dynamat, but at a fraction of the cost. I installed it from the fire wall to just behind the side door and have been very happy with the results. I get quite a few comments from passengers about how quiet it is when traveling. One thing I learned when researching this, is that a lot of these types of products produce an offensive odor, especially as temperatures increase. Fatmat has no odor at all and is easy to install. I highly recommend it. Bob