Bear with me its my first time. I currently have a 2006 3500 megacab 4/4 with a automatic tranny. I have 140,000 miles on it and just spent $3500. on the tranny. The shop i took it to put new clutch packs, a midwest torque converter, a billet input shaft, a shift kit, a new band, and a mag hitech deep tranny pan in. I also have a banks automind, exhaust, and air intake already on the truck. There is a 2" leveling kit in the front and air bags in the back. I also run 285 cooper st tires. My mpg inproved from 17.5 to 20.5 highway and from 9 to 10.5 pulling my 8 by 16 h&h cargo trailer. Is there anything in the $500 to $1000 dollar range to gain even more?