Diablosport Sprint AFMM
2015 GMC Sierra 1500 5.3v8 Only have about 200 miles so far and my first impression is mixed. No more rough shifts and hunting in the transmission, good thing more power and smooth acceleration, good thing, reverted to 4cyl mode while driving in the city, bad thing lost about 1mpg or so, not a big deal. I don't know about parasitic power drain haven't checked for it yet, was able to get back to v8 mode by removing and reinserting the sprint device will have to wait and see if it happens again.
Hypertech Max Energy 2.0 Programmer
it seems like a good product but i am disappointed in what function are ACTUALLY AVAILABLE for my year and model truck. the advertising is a little confusing as it shows all the functions and then says choose your vehicle, not knowing that all these functions may or may not be available for your model. It does program nicely.