We used a bullydog in our 2012 Ram 2500 5.7. We liked it added mileage to the tank and some good power.
We didn't go over board with the tune. Changed the shift points slightly and set it at moderate tune.
We pulled a 40' Bunkhouse with it and on our trips we could keep the truck at 10-11mpg.
We also did a cold air intake and we cut just the muffler out and welded in a 40 series flow master muffler.
Whenever the truck went into the shop they never gave us a hard time about the tuner and did all the warranty work.