The area above the driver and passenger seats can heat up like a pizza oven. Between the headliner and the steel of the van there is just air. Filling this area with insulation will slow the air movement, provide density and sound deadening. After completing the insulating of the van it became very quiet inside. Very much worth doing. This is easy to do, but it did take more time that I had anticipated.
Part 1
Part 2
Part 3
Trim Removal tools
You will need these tools to make removing panels easier.
Trim removal tools- https://amzn.to/2ZZq1s6