I have a 2008 ram 2500 4x4 mega cab with 6.7 and a manual 6 speed. It was fully deleted, A&E air intake box and tube, 5" turbo back exhaust, with H&S Mini max, 305/55/20 tires when i bought it. I had seen upper teens and even low twentys for mpg. I have since put on a Banks Monster ram intake, Banks intercooler with all new bigger tubes, and went to stock size rims with 285/70/18 tires, put in a new Valiant dual clutch kit. And just recently had head redone and installed ARP head studs. Now I'm only getting 15-17 mpg tops. Any ideas why its getting worse MPG?