I want to add some foam or some sort of material to the rear section of my coupe to absorb some of the noise that comes from the highways. I was thinking of adding some dynomat or thin foam around the spare tire and under the rear sections to quiet things down...

Anybody ever done this?

 

I haven't used it in cars. But I have used the 3m stuff on airplanes. I think I got it from Aircraft spruce, been too long ago. That stuff makes dynomat sound like crap. How much of a difference it would make on a car..?

 

Plenty of people have done this....check the audio forum for all those posts.

 

or get better tires, stock tires are insanely loud, even if you don't have the feathering problem.

 

+1
After market tires are a big upgrade concerning sound transmission. I replaced my stock Potenzas with Kumho Ecsta ASX's and it's an amazing reduction in road noise....it's even more fun drive now.