Chassis foam, interesting stuff..

[Dairy King]

Chevy is doing the quiet steel stuff, too. Atleast on the Equinox. Its two pieces of steel with either rubber or some kind of cloth in between. My science teach in high school bought one, and they gave a sample square of it. It was neat, there was no vibration or sound if you hit it with anything, no matter how you held it.

 

[vermilion]

innovative.