:thankyou2:I have a 01 diesel w/ a banks 4" exhaust, big head wastegate, nv5600 6 spd. 245 75r 16 general hts tires, 75,000 miles, k&n filter, otto mind, boost, and ex. temp guages. When I tow 12k in the mountains on a 6* grade, I'm only going 40mph at the top, and getting 14mpg. I'm thinking of...