I can agree with that, the mileage is a little better. I believe it was in the 18s on pump gas when I installed it. It's just under 20 now but I've switched to rec gas over the last many months so not exactly an apples to apples comparison there... What's drastically improved is how much MORE I enjoy driving it! The throttle LAAAAAAAG and gear hunting on hills used to drive me nuts!! I cleared the tcm adaptive tables so many times but this 5AT never got much better. IMO the SprintBooster is the best way to address the how the 4R drives lifted on 275's. I'm considering buying another SB for my GX one of these days. It needs help with the 32s...