If I could do it again, I'd buy the mass back. I saved a few bucks and went with the poly, but when it arrived I found it was much lighter, and there certainly is much more road and exhaust noise in the cabin. I actually discovered that my cat was rattling...something I hadn't heard before.
I'll take a stab on this one. I'd go with the mass back as that is what your car came with. The poly backing is o.k. but just seems "cheap" in my opinion. As far as prices and quality.......try Corvette America,Wilcox,Mid-America,Corvette Central, they all seem to carry the same carpeting so it might just be who's got the best $$. For the heat barrier, can't hurt, I wouldn't think it would weigh that much. Hope this helps- Doug
A few years ago I bought mass back from ACC, through a well-known vendor. The front carpet is fine but the rear carpet is very poor quality. Over time it has warped, it is all bumpy and wavy, I am ashamed of the rear hatch area in my car. Worse, It does not bend the way the factory carpet bends, the rubber has actually cracked where you open the storage bin doors.
I replaced the carpeting in my '96 Grand Sport about a year and a half ago and was asking the same questions you are. I bought mass back from Willcox. The price was great, and the carpet is great, too.