If you have a 99-up I would definitely go with 4.10's! The rpm difference is minimal to a 3.73 and the feel is way better. But that's just me but if your going to put your car on the track then 4.10's all the way.AZ Diff got me in on a Saturday morning and it was done by noon. Changing the gears made a huge improvement, but I may now be going 4.10's. It was suggested that I go 4.10's in the first place and now I know why. No matter what you go with you will love the feel. Good luck!