The build began with some sound deadening. My first priority was to keep as much sound in the truck as possible and keeping as much outside noise out. You can spend tons of money on vehicle sound deadening but there are much cheaper ways that are just as effective. You need only to stop by your local hardware store and pick up some peel and stick flashing and elastomeric roof coating
Here is the truck with the storage well carpet and rear cab liner removed.
Peel and stick roof flashing strategically applied around the small amounts applied at the factory. This stuff is largely asphalt based. This is good for sound deadening but can smell pretty bad when the temps get up... even with the aluminum facing. (Tape was used to cover the places I did not want getting coated during the next step.)
Painting everything with the elastomeric roof coating adds deadening and seals the asphalt smell that would otherwise permeate from the flashing. You could skip the flashing and just use this product but i find that they work wonders together.
The cab is so quiet now. You can't even hear my exhaust with the windows rolled up. My wife has already requested i do the same on the passenger side floorboard.