I have an 07 5.9 4X4 Dodge Dually with a G56 stick. I run 285 Nitto Terra Grapplers on it with a 373 geared rear end. I am at 2,000rpm at 65mph on the highway. how much does it drop your rpm and how much fuel mileage increase do you see??? I have wanted to do this for a long time. 30K and it...