We use closed-cell foam in two thicknesses for the engine bay firewall, footwells and behind the dash. Others have used this foam for under carpet layment.  How you use it is up to you. Here is a pic of Merlin getting covered with his foam. This item is for a sheet of 1/2" foam. We will supply you with a drawing of where the different size foam goes and what WE cover with the aluminized foil. The rest is up to you and a bucket of glue!  Not eligible for free shipping, shipping $25.

For the complete, original firewall you will need two foam kits 1/2 inch and 1/4 inch - Part Numbers P49/22 and P49/23 and the Firewall Foil P49/20.