I got some of that stuff at NAPA. It's inexpensive. It come with reflective on one or both. It's hard to cut. The reflective surface is not very abrasion resistant.
I used it on the inside firewall to reflect heat away from my relocated ECU. Don't know it that matters but with that old a computer, and the fact when I modify thing I open pandora's box.

It must have been the weekend for it. I had some left over from when I did my Raider. Its been taking up space for about five years so I put it to use on my Passats floor boards to reduce tire noise when I drive on rough roads.

I drive on RT 26 in the Portland area, a very noisy road. It really did help... Now I need to buy some more.

The Dynamat is a damper material. A thin sheet of elastomeric with an aluminum cover. Just over the wheel opening I used three layers. Further away from the noise source I just used two layers, tapering off to one layer.

It seems to stop the floor from being vibrated by the tire.

When I did the Raider I also did the roof. It does seem to work pretty well and its thin enough to put a stick on headliner over it.

Fun stuff,

Kevin

I looked around on the web and found similar material to what we used in yacht building industry.Looks to be reasonable.soundproofcow.com what I'm looking at is called Quiet Barrier.4 1/2ftx20ft roll $118.45 and probably is not self adhesive.

Here is the stuff that I am planning on installing this summer

Rattle Trap

They make some thinner stuff also called FatMat

The Land Cruiser crowd loves this stuff because of its "lower" cost when covering the expanse of an LC interior: http://www.secondskinaudio.com/vibration-mat/damplifier.php

Check out their other products, too. They have some pretty cool stuff.

Funny, i ran across those sites last night. Of course, they all say they are better than the other guys, but I wonder how close the actually are. both of those dynamat alternatives are quite a bit cheaper than dynomat.