firewall insulation
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The tar-soaked fiber-board stuff is what GM used in the 60's & 70's. It dulls out higher frequency sounds. I don't think you can buy that stuff anywhere; but you want something which is relatively thin, still has some mass (heavy for its size), and is flexible (can't be solid and hard) so it will absorb the sound but not transfer it. If you can easily cut it with box cutter, etc. it will be easy to cut shapes to fit on floor and other cabin surfaces (under the carpet) to limit sound transfer to the passengers.
