My headliner was already in with the cheap foil bubble stuff. So, I used it under the dash, in the doors, as much as I could in the sides through the small access holes, and in the lower sections of the cargo doors. The doors now "thud" instead of sounding tinny. In fact, only the lower third of the cargo doors are done since there is no access to the upper two thirds without cutting them open. Noticeable difference!
Coverage, get out the ol' tape measure and figure out the square footage. My plan wasn't to cover every square inch and the stuff did what I needed it to do.
By my rough calculation, one box will cover 25 square feet. The flat floor alone is, what? Probably 9-10 square feet? So, one box might do floor and firewall. Another box to do roof and back wall? You're not doing so bad at around $120. And you added 40 lbs. Just make sure the surface your sticking to is clean and stick worthy.
