Originally I was using mine when my only mods were a CAI and cat back. The three working together I could get 22mpg on the freeway. After the OME and 255s I could still consistently get 20 and at time 21mpg. I noticed a significant improvement in power too! Even after the lift and tires I could get up to speed faster than stock. It wasn't until the 295s went on that the power wasn't significant. Now with 35s the Hemi is still a beast only it struggles a little under 2000 RPMs. Any time I restore the tune back to stock I can't believe what a difference it makes. I am not sure why you guys are having such a hard time with it, but I hope you can get it figured out!