Google Groups : rec.autos.makers.vw.watercooled: "When my wife and I put the interior back together in her Jetta after the
VR6 swap, we put down a 'sound proof padding' (with foil!) that I picked
up at Pep Boys for like $10 a roll. Two rolls were needed. This stuff
looks like it was made from link pulled out of random pockets at the
laundry matt, and it has a silver foil on 1 side. Easy to cut with a
sharp knife."