there are many great damping materials out there
Quiet Steel is about the best, but thats more for factory deals
Dynamat extreme is about the best designed for car audio.
brown bread is good as well.
common alternatives are
Raammat
fatmat
Edead
bquiet extreme
Second Skin
All good products.
I would avoid roofing material though
lower tollerance to heat in most cases and smelly.
not all, but most
ANT