I also recomends blackbear. Don't even need the autocal. Do the mail order tune or even better, drive for one of their in person tune events. Fast, and definitely the best people. They are pros who know these trucks inside and out. 5 star service. No other tuner will treat you as good as blackbear. They even helped me solve a problem that plagued my denali for months and the dealers couldn't even figure it out with their fancy tech 2. And it took them 1 look at my data logs to do it. Can't recomends them enough
Range device doesn't reprogram anything. You can pull it out and it goes right back to AFM. No dancing with the dealership. I bought one. It worked but I returned it. I just didn't care enough about the V4 mode (I like it on highways, get much better mileage) to pay hundreds to disable it.