For some strange reason my excavator has carpet like material with some type of foam backing on interior of cab, except for firewall (behind seat). I am assuming they didn't put anything there as it does warm up after 3-4hrs of steady work. I see they put foil backed insulation in engine compartment up against firewall. During this semi-annual tune up, I ripped out my floorboards and rubberized all edges where they mate with each other and filled all cracks with rubber. Now, things have stopped rattling, but the tin can is still loud (improvement though). I figure if I can find something to stick on the wall behind seat, I will stop sound from bouncing around. What sort of material do you think would work? It has to take a little heat from time to time and cannot be toxic if heated or frayed. Is there something NAPA would sell for cars? thx.