hey men! I have a 03 QC SB with the HEMI. its leveled with a 3'' body lift, running 35x12.5x17 all terrains. i get like 10.5 on city and 13 (15 if I'm REALLY lucky) on hwy. i know its a big ol truck with big tires, big engine, but this sound pretty low to me haha is there anything i can do to improve my millage?