I can feel a slight difference when the MDS kicks in, but it's negligible. With the a/c cranking and a BakFlip, I'm averaging 19.5mpg. That's roughly 70% highway, 30% suburban, and the highway mileage is the DC Beltway which can be stop&go. The truck's only got around 1,400 miles on it.
Maybe it's because I'm old, but I really don't care how the truck sounds to people behind me when I'm commuting, especially when I'm getting this kind of mileage out of a truck this big and this powerful.
Am I missing something here?