I have an 06 2500. I run a Banks Stinger, the 100 horse version. I never use more than the 50 horse pulling an 03 Jayco Designer Elite 3610 RLTS. I have 193,000 on the clock. I also have a Banks Monster Exhaust, cold air mod and Banks Speedbrake. I get about .7 mpg improvement which is 8% better than stock when towing. Drive-ability is improved, truck just runs better, idles better, turbo spools faster. Things to know; the trans learns the tune so pick the level of increase you want to pull with and activate tow haul. Use the same setting each time when in T/H to reduce trans learning and possible slip. I run level six when not pulling, all the time. I get close to 2 mpg average improvement in this mode. Your torque converter is the weakest link, and will slip at 100 horse adder while pulling. I slipped mine on an Interstate onramp. The trans, if well maintained, SHOULD be okay with the Stinger,but I don't need that much for towing. Next thing to go would be the C3 clutch pack in the trans. Installing a TransGo Jr. kit is beneficial to help with slip.
More thoughts; I never felt like my truck in stock form was under powered, including almost all of the mountain ranges in the 48 contiguous. It is better with the tuner, but you will find the weak link in your drivetrain. I have the speedbrake, best addition ever to any truck. Down hill cruise control at it's finest. BUT, you can cause the trans to slip with overly aggressive use of the brake. It is using the variable turbo vanes and the trans to slow the rig.
Summary; love mine, but expect to have earlier failure in the drivetrain as a result. When that happens, I'll have a built trans and triple disc converter installed. Have to pay to play. There is a definite domino effect here. If you add power, you reduce reliability overall. On the other hand, when all is upgraded, you'll have a pulling monster.
Craig and Cheryl with our dogs
Buddy (Maltypoo), Sally (English Springer)and Charley (King Charles Cavalier)
'06 Chev Duramax LBZ
'03 Jayco Designer Legacy 3610 RLTS