2001 Suburban 5.3L which was very anemic before I bought the I3 tuner. Was skeptical with the Plain Vanilla appearance, and lack of full display, but it is not lacking in the Performance Department. I first used the Default 87 octane setting. I pull a 26 ft Warrior Toy Hauler with a Honda GL1800 Goldwing in the back, that bike adds 900+ lbs to the load. The Suburban is being asked to pull more than tongue weight rating, doing a super job and added 3+ MPG while towing.
Device does what it claims to do; prevent vehicle from shifting into V4 mode. This doesn't completely stop the annoying vibration that occurs between 1000rpm and 1250rpm. I believe there is some other inherent deficiency that Chevy can't diagnose or chooses not to address. This vehicle should not vibrate or shudder at a certain rpm.
2015 Chevy Suburban LS
Turned off the AFM, stiffened the trans 50% made few other adjustments. The AFM in vehicles is a joke! I have driven roughly 1000 miles since I programmed my suburban and I am getting better gas mileage by 2mpg (not much but better). I have no other mods to my burb at this time. Definitely better get up and go from the low end. Shifts feel a little stiffer. Actually fun driving the suburban now. I drove it for 26,000 miles before the programmer. I can feel the slight changes in the drive.