Does anyone have experience with the "Truck Edition" engine control module. I have been speaking with a person that has installed one of these units ( plug in ) and says that he is getting 12 to 13 mpg puling a 14,000# fifth wheel and gets 20 mpg driving alone. According to Truck Edition their module does not down load into the existing ECM, but works in conjuction with. The module is supposed to increase HP and mileage and keep the EGT in safe factory range. If you unplug module it is not suppose to leave in tracks in the system. This module sounds to good to be true.