I put it up the inside of the firewall too, but the header/heel issue was a better example of how well it works. Others that buy better headers won't need the floorpan covered, which is good cause it's pretty thick.

Do you recall how much of it you used? It comes in sheets 4'x6'

Neoprene works very well under the carpet and at firewall. Jute is also great thermo isolation, just looks old school and hard to come by now days. There are neoprene rolls even with one side shielded with tin foil and adhesive on the other. Just gotta look at different surplus places and suppliers...

Sorry, just saw this question. It's been a while so I don't remember exactly. I don't think it was more than one sheet because I bought a Scrap the shop had laying around. 4x6' covers a big area on these smallish cars. If I pull the carpet out I'll let you know for sure. I was focused on the drivers pedal box area and the firewall directly behind/above the engine/trans.

Can I revive this to see if anyone has delved into the aerogel option? Scientifically it has some of the most impressive heat dispersing properties. The C7 uses it on the tunnel