Mickey's 4.8k quote is probably of StandartPlast Silver (StP - Home) which is an internationally known sound damping and deadening company founded in Russia.

Brand name power lang yan. For a more accurate quote, it's best to ask how much do they sell their sheets. That way, alam mo yun price difference of the material (sheets) and labor and this could give you a better negotiating leverage.

I don't usually discriminate on deadening. Habol mo naman dyan is mass -- the brand name? Not to much unless you're willing to spend extra. I do appreciate my StP's easy-installation process though and they use higher grade butyl (yep, meron din yan quality grades) for their products so if you're competing, these are usually justifiable expenses. If not, stick with the OEM mass market butyl ones.