Since I bought my wife her Suburban, the AFM system was driving us crazy! It would kick in and out and cause a terrible exhaust drone that bothered everyone. Since purchasing the Range AFM Disable Device, we actually enjoy taking the Suburban out and getting constant and consistent V8 power. Gas mileage has stayed about the same @ 18.5 mpg but without the lag of the AFM kicking in and getting "tripped up" on itself and not shifting correctly. I highly recommend this product!
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.