I installed some similar items
I got from Menards;
-WeatherGuard (Peel-N-Seal copy) - only a few fractions of an inch thick, this provided a good stop to vibrations.
-Frost King duct insulation (Similar to Dynamat - has aluminum backing - USE GLOVES, CAN and DOES cut fingers if you aren't careful around cuts)
-Reflectex duct insuation - (tranny tunnel and floor only) This kept transmission tunnel heat out of the car.
This was installed on the:
-Door panels (inside of outside skin, inside of inside)
-Floorboards and transmission tunnel
-Behind the seats and in the trunk
Overall, before install the car was a beast as far as noise. It was loud and not quiet about it. However, post install I found the sound dramatically decreased and unless I'm boosting, driving over harsh road surface (or have bad tires) I can only hear the exhaust for the most part.
We have to pull the dash to replace it and when we do I will be adding damping material to the firewall as well. This is where the majority of the noise and heat comes from now, though I have yet to do the panel behind the seats as well (I have a vibration in there on my car too...)
Overall weight gain was probably less than 10 pounds, overall enjoyment of car with no A/C? Cross country tour approved.