check w/ a stereo shop that does auto installation
or
a big auto super or hot rod store
it does not take much to kill the tin sound
but some think that the single or double sided heavy foiled outer w/ jute material inside is true sound deadening material, that helps kill the tin sound and acts as insulation, products like Dynamat kill sound or that tin noise but do nothing for insulation.

some of the big box store roofing supply products give off a chemical when it gets hot inside the cab during summer.
as far as the tin foil tape go to a heating and A/C company. it's called furness tape used in that industry. you may find a do it ur-self type heat/ AC company and can buy it that way.
