Got some of that under carpet sound proofing, the kind like really thick tar paper. Can I just heat it with a propane torch to get it to lay down flat on all the contours. Not hot enough here to lay it out in the sun.

 

Hair dryer will do it

 

Hair dryer or if your wife/ girlfriend doesn't want you using it in the garage, use a heat gun. Have a razor ready to cut slits for corners. I use mobile home roof repair found at Home Depot. Works just the same as dynamat.

 

I was pretty unimpressed with the tar paper soundproofing I got.
You might consider Dynamat, Fatmat, etc if it's not factory correct resto.

 

Yeah you can use any number of petroleum based roofing materials to sound proof underneath the carpet. The problem is you will run the risk of your ride smelling like tar. Frost King insulation would be much better before you spend the money on Dynamat