Tar board floor insulation

Has anyone ever used a Tar board insulation material on their floorboards under the carpet? I found a kit at Cal Imports Parts. It states it will insulate and reduce noise. Pre cut to fit bugs so I figure I might just need to shorten the rear pieces. So if anyone out there have tried this stuff please post your opinions.
As Always, Thanks
Larry

Anything will help, from tar board to thinsulate to Dynamat. If your only doing the floorboards don't expect much cockpit noise reduction.

When I did my carpet I bought auto underpadding and cut them to fit on each side of the center of the car. Under the seat square. Then I reinforced the material sides with duct tape. Feels great under the carpet and it does insulate. Easy and cheap!

Check out this link for all you insulation needs:
www.quietride.com/index.html

Copied from old post:
posted 11/8/2002 4:20:14 PM
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When I was doing auto upholstery, several years back. We didn't use Dynamat because of its cost. We used Bituthene, it is a membrane roofing product used on commercial roof tops.
I swear that it is identical to Dynamat, only about 1/60th the cost. They are both rubber based, adhesive backed membranes. Bituthene is available at any roofing supply store, problem is you don't need a 100 foot roll. Perhaps by asking a roofer, you can score a few feet of it.
Bituthene is the trademark, generic name is, self-healing bituminous membrane.
-=theron