I’m getting .1 better after I turned it off lol. I reset one of the tripometers when I did it to track the difference. Obviously it’s not real scientific, but hey it’s not several mpg worse either. I haven’t had any issues with warranty, but I’ve also only ever made one claim; and that was bc the haptic motor on the left side of the driver seat went out. I turned it back to stock prior to taking it in for that, I have left it tuned for all my oil changes there though, I get them done at the dealer I bought it from. Diablo claims the gm techs can’t see that you’ve used their product once you return it to stock, There’s plenty of debate over that. I was closing in on driving beyond any mileage the standard warranties would cover for any power train related stuff, so I went ahead and did it. I’ve since messed with the firmness of the shifts and some little things like that, but it’s all still the “canned tunes” options that come with it, I haven’t had a true tune. To me, It’s one of the best investments/mods I’ve made/done. If anything, just for the peace of mind of knowing I don’t need to concentrate on how I use the gas pedal in certain scenarios, I can just drive and enjoy the truck. Sent from my iPhone using Tapatalk