I used lizard skin and like how its applied, works and how it looks. Easy to use. Can be painted over. There are two types, one for heat and one for sound. There is a sequence for applying them that I can’t remember now. Would do it again. LS also worked well For spaying the undersides of fenders to prevent star cracks from rocks etc.
I've used Second Skin in two cars and been happy with the results, good sound deadener and has an aluminum shield on the top side for heat. I also put in the doors and quarters to take the tinny sound out when you shut the door.
The last 3 of my vehicles I've use a product called NOICO, its available from Amazon (36 sq/ft, .080 thick $68). Its a cut to fit, peal & press, and roll in tight product, foil backed comes in silver or black ($2 extra), and could be painted. Its Bute based so no smell and runoff problems related to the asphalt products. The temp range is 220 down to -40 F. Gene
I used both types of Lizard skin on the underside and inside of the floor pan, then just because I wanted to make sure the heat from the exhaust would not penetrate I installed Hush Mat on the inside of the floor pan and firewall. Kind of an over kill but the floor is cool. Some procedure for the doors and quarter panels.
The Jalopy Journal
