Sheet lead is by far the best sound deadening material, but it has to be
freely
suspended from vibrating objects/surfaces---1" soft foam + 1/16" sheet
lead
is very good..

Rick wrote:

What produce can I use in my Hi-performance VW in order to keep the
noise out of the passenger compartment? My wife is having a hard time
with the dual carb, header situation when we go for a sunday fly, I
mean drive.

Rick
Bass Players Drink Bass