I have noticed and increase in mileage. Nothing earth shattering. EFILive would be better, but hind sight is 20/20. Only drive it on 5 if you wanna race. Or your brave. It won't kill anything, it has some safety features in it. But you can limp your tranny on 5. I have done it. Not sure what version I am running now. I know I did update it once after 2.3. Might need to update now. lol