did anyone come up with a reason for the bad fuel mileage? i have 2000 dually crew 2wd 3.73 gears auto trans hypertech on stage 2. 4" exahust, no cat or muffler cold air intake. got 8 mpg pulling a 38 foot goose neck 7k empty 8k loaded with bikes. just ran 5 tanks thru it going to mississippi...