Sound Deadener
I used the Noico stuff from amazon & put it everywhere I could. Floors, under door panels, trunk, wheel wells. Used some aluminum a/c tape from Lowe’s to seal up seams. The Noico aluminum is thinner than dyna mat, so it tears sometimes if you stick your thumb through it working it into places. I just covered those with the tape.
I had trouble initially getting it to stick to the firewall. Cleaned the firewall & it stuck. After a couple of temperature cycles the stuff bonds to the car & you can’t get it off even if you try.
It has really quieted the car down a lot. Mine is an a/c car. The mufflers are kind of loud, but With the widows up, it is pretty quiet on the inside.
I might have used about 100 sq feet.