Carpet and sound proofing.
Click on the
SEARCH tab above... type in carpet or sound proofing and you will be amazed at the amount of info that is readily available.
Heres an example link:
http://www.forabodiesonly.com/mopar/showthread.php?t=219230
FYI- I used Peel and Seal from Home Depot/Lowes as heat barrier/sound absorber. Its in the roofing department and a less costly but effective option.