I have a 2000 crew cab short bed 4x4 powerstoke with 18" wheels and 325 by 33" tall tires and 3:73 gears. The mods I have done to it are the napa filter, dp tuner chip with the 100 and 140 tunes, 5" stacks with a stock down pipe, and a bd tranny with their 4r100 converter. My dilemma is I get almost 16mpg doing 75mph spinning 2150rpms unloaded and almost 11mpg doing 55mph spinning 1700rpms towing a trailer with a rhino on it and a combined weight of about 3000 pounds. And around town I get roughly 12 to 13 mpgs driving easy for the most part. So my question is with this given set up, I think I should be getting better mpgs and even if I should or shouldn't, how can I get better? I want to ditch the stacks because they just draw unwanted attention so what would be the best exhaust setup for mpg's if it were dumped out the side behind the rear axle like the stock setup. Thanks in advance.