Here's the stuff I used:
http://http://www.lowes.com/pd_28929...ductId=1081449
It's FrostKing insulation. Foil on one side and adhesive on the other. It's the stuff recommended in the ERA build manual and it worked great. Maybe it's belt and suspenders, but I also used jute pad between this stuff and my carpet. Nice and quite (except for the sidepipe noise you want to hear) and no heat issues coming into the cockpit.
Matt