I did the doors on mine. I did 80mil butyl and then the foam on top of that (both noico). Be careful at the to of the inside of the door, too thick of foam and the window interferes when rolling down.
I also removed the b pillar panels and did those at a later time and noticed no difference.
The dog house and floor are both 80mil and the thicker (315?) noico red. Then I also did some on both sides of the firewall.
The biggest thing that helped my noise is the fan clutch.
2009 Supernova 6372
Sold: 2005 6316 Ultra Super C