I primarially bought this to disable the DOD/AFM on my '16 Silverado which was a simple process. I also loaded the 87 tune. Both changes I can confirm increased my gas mileage. It wasn't a lot, maybe 1.5-2mpg during these summer months. The DOD/AFM is an issues for these trucks at high mileage, the cams go bad and I was hoping to prevent this from happening to my truck. With the 87 tune loaded, the transmission has a better feel to it, it's not constantly shifting around anymore and now holds it's gear better. There are a lot of options within the controller, a lot I will never use. The price was a bit high, and due to the low miles I drive, this will never make it worth any gas savings. What I'm hoping for is no cam failures though. Time will tell...

I have a 2014 Sierra Denali with a 6.2 L engine. For the last couple of years I have dealt with odd transmission shift/surge. It was hard to tell what was actually occurring. It was as if it was confused on shift--especially 2nd to 3rd on the factory 6 speed transmission. It also felt like it was surging on accelerations and "clunked" on downshifts. I just felt like it was somehow in the programming---somehow a file maybe had become corrupted. So I took it to the GMC dealership. I asked him to re-flash the programming. He drove around the parking lot and said I needed a new 5000 dollar transmission. It was not bad enough for me to spend that kind of money yet. Besides I didnt totally buy that story.
So I carried my GMC to the Chevrolet dealership. I asked him to re-flash the programming. He said it was 90 dollars. I agreed. In a few minutes he came back and said my truck was parked around front and ready to go. He said there was no charge because it had the latest version and they didnt do anything. (Noone listens to the customer anymore.)
So after research I thought i would try the Predator. How could I go wrong? Amazon had the free returns on this unit. If it didnt work, I return the truck to stock and send it back.
I decided to ONLY change to Economy Tune. The 6.2 already has 420 stock HP. (Im not sure my neck could handle any additional HP.)
OMG!!!! What a miraculous change!!!!! For 350 dollars I have a BRAND NEW TRUCK. It totally fixed the issue!!! The supposedly "wore out" transmission shifts perfectly! No more surging! No more hunting gears! No more Clunking. It is a smooth perfect shift up and down. I actually believe it also it feels as if it has added some HP. Maybe just a more efficient shifting transmission computes to more HP.
Also an added feature is that I am seeing an additional 3 MPG on the Denali computer. How long will it take to make up 350 dollars in that? I think I will box up my Predator and put it in a safe place. I will leave it as it is.
Maybe I will drive it up to the GMC dealership and let the guy drive it. I will ask him how he likes my new transmission.

Update a month later
I decided to go in and turn off the 4 cyl mode deactivation. Wow that is better also. I did not realize but the engine shutters a little when going back and forthbetween V-8 and V-4. I was just use to it. It runs sooooooo much better and no noticeable difference in gas mpg. You can go into the display settings on the truck and you can watch it displayed whether it is V4 or V8. When it is changed, it will stay on V8.

Did everything I wanted it to and a very good description of the product before I bought it I am sure I was buying the right thing before it was delivered

Haven't tried any of the tunes yet but it worked perfectly for what I bought it for. I was able to turn off the annoying DOD AFM feature on my 2016 Yukon XL Denali to keep it in V8 mode all the time. It worked right out of the box with no update required.

Have not found anything to dislike about this programmer. Sport mode is crisp and quick. Tow mode to be tested this weekend. Well worth 400 bones