My cousin is using
this on his lifted '07 GMC and has loved it! Along with the performance gains, he really loves that it's a programer and you dont have all the extra crap to mount on the dash. It took care of his larger tire size-speedo issue (speedo is spot on now) and the truck makes great power. He tows our dump trailer, that's a few thousand pounds empty, loaded down with building materials with ease. And on the weekends he tows his enclosed trailer w/ the drag boat, ect in it...that's a 12k # package. He's towed that from OR to AZ and back with ease.
I'm not saying it's the best...just saying he's happy with it
!