I drove one last night. I have to say, I have had many loud exhausts on Trucks and muscle cars, but I preferred the sound of the turbos spooling over the loud exhaust.
IMO adding an exhaust or trying to make the truck loud would not allow you to hear the sweet turbos churning!
The truck was quick. It was snowing out - probably 1-2 inches on the ground. Put it in 4wd high and it ripped around a corner and up a hill with no slip or hesitation what so ever! Very impressive.