Quietening my Humvee has beem my lifes work....
The first things are the rubberised airhorn, fitting the DWF kit rubber elbow below the mushroom cap air inlet, fitting some rubber strip between the fan solenoid (Cadillac valve). These are easy and give amazing results for the effort.
Then seal up every hole, fit insullation inside the beam under the windshield (there is a cover you remove in the engine bay under the cross beam that gives access.
Fit an Artic kit insulation package inside the truck. This gives more of that green padding and covers up the tunnel and sill plates.
Next is the harder bits, dynamat under the dog house cover and everywhere under the transmission tunnel, over that fit a barrium loaded, foam insullation with a silver mylar cover over the dynamat (this stuff is commonly used on boats as a liner for engine covers. them over that fit aluminum foil heat shield sheets to seal of the foam off from the mud and water. These sheets are secured to the cross beams on the body by screws and large washers.
After you've done all that, you can listen to music as you drive along...
But, no matter what you do, it will never be like driving a car.