I have a '99 cummins auto 4X4 with 4" turbo back muffler delete edge juice w/attitude and I am getting 19.6 on the 2nd setting, tow, at 60 extra HP. On the mileage setting I got 17.5, thats 40extra HP. I figure with a air intake and some new tires I could get over 20.I have a 99 CTD 4x4 and had 2 questions.
1. I have a Hypertech Power Programmer III, it has 3 stages and I was curious as to which would give me the best MPG.
2. Do stacks or straight piping the exhaust increase your MPG.
Thanks for any input.