I'm very late but I may have to get the 4.0 for my setup. I'd still leave the factory 6th in tho. I mainly want to stretch out 1-4 longer. I'd prefer to trap the 1/4 mile in 4th compared to 5th like I was. We'll see how my 4.3 works then go from there. But deff a nice review. I'm liking the gas mileage part. Lol