Torn on this. Have a 2017. Getting close to getting bigger tires and wheels. Don't really feel the need to pay the dealer to flash my odometer if I can just put that money towards a tuner. Hemifever doesn't seem to be too afraid of warranty issues, but many others on here would never do it. I tend to be more on the risk it side usually.
Would there be any difference between say a 2014 with its unlocked ecm being tuned, then back to stock for a dealer trip then re tuned. Versus me buying the new unlocked ecm and giving mine back and doing the same thing. I really don't think they will dig into it enough to ever tell. Unless like my engine failed completely and it was a huge issue they might. But the odds of that are probably the same as me getting hit by a car walking down the road so I"ll roll the dice.
Had a custom tune on my previous truck a silverado using a Diablo tuner and Diablolew so I'm familiar with the process. But that truck was out of warranty when I bought it.