this is just my experience..my stock gears were 3.92's, i wanted to gear up and went to 4.56's..loved them. Then bowing to peer pressure saying i would do better at the track I switched to 4.10's... i guess if i went straight to 4.10's i would feel pretty good about them, but going to 4.56's, and then dropping to 4.10's..left me wanting more whenever I drove on the street or track. So when another member was giving away 4.56's since he was buying a diesel I jumped all over that and have been in driving ecstacy since. i swear by 4.56's and never run out of gear..and i run 12's in the 1/4 on 28" dr's or slicks... as for mileage, this may not be accurate but it works for me.. I also run 17" wheels/tires on the street..