Dynamat is a dampening material. Cars come stock from the factory with dampening material. For example, luxury cars have hundreds of pounds of dampening material to dampen everything from road noise to engine noise. So if you had a bell hanging on a string, and you tapped it, it will resonate. If you dragged the bell along the ground, it will resonate. If you put a small strip of dynamat on the bell and tap it, it will resonate but only briefly. If you dragged the bell along the ground it won't sound as loud. That's the idea. The more dynamat the better. The thing is that dynamat is so much heavier and "damper" than the original stock stuff, you need to invest dynamat onto every surface of the car to get benefits. You have to cover every inch!! :)

Calvin

Calvin