ive never used spray, i use dymanat frequently (all the rubber damping products are going to be more or less the same) i would go with a peel and stick style, dense rubber, then a closed cell foam like dynapad (or equivalent) over that. the rubber mat reduced vibration and the pad absorbs noise (exterior and the like) doing your whole cab floor roof rear wall and pillars will greatly reduce the noise floor in the truck. down side, less turbo

 

Not to worried about less turbo noise. Have the S475 which loves to sing.

 

I'm planning on doing "mat" style. Before buying Fat Mat, look up the reviews. It's owned by the same person as "peal and seal" the roofing stuff. Make sure to get a butyl based deadener......no asphalt smell

Check this stuff out:
B-Quiet | Home

 

I bought a gallon of Spectrum Sludge from Second Skin in Tucson.
After removing the bed, we applied one coat to the back of the cab and one coat to the front of the bed.
Then, a second coat to the back of the cab.
It's a little quieter. :thumb
I have half of it left, so, I'm going to put it inside, on the floor and rear cab.
With Dynamat on top.