My parts car has a thick felt paper (like roofing felt) lining applied with a thick tar-like goo in the trunk and cabin, whereas my car (earlier build date) has a thin layer of felt (kinda like dryer lint) throughout. I guess the Motorsport people were experimenting with their sound deadening techniques.
The reason I bring this up is that the last time I weighed my car it was 3240 lbs., which is considerably lighter than advertised spec. (I think 3400+lbs).
How much does your car weigh?