In the aircraft Spruce they sell sound insulation in various price ranges. I bid some 1/8" material on E-bay for car sound insulation, I plan to use that on the belly pan, belly fabric, bottom of floorboards & wherever I can up front. I brought a roll of fancy bubble wrap insulation with air barrier on one side and aluminum foil on the other. I plan to put that in the overhead, sides & back. This material is supposedly R-15 and passes the basic burn test (doen't support combustion, and emits no noxious fumes and have documented burn ratings. I bought a pair of Kevlar fireman's pants at the army store and am having a seamstress make me an outer firewall cover, than will use the black closed cell foam out of A. Spruce to do the inside of the firewall. Some IA's like to push their weight around about the stuff being non certified if they want. better talk to them first. I am spraying my headliner with the liquid fire retardant that Spruce sells...Ken