I went from 3.73's to 4.10's on my stocker. Made absolutly no other changes at that time.
Car went from mid-high 1.7 60's to low 1.7 60's and gained 1.5mph in the 1/8. It was the difference from running 13.teens to cracking into the 12's.
There is a difference in fuel mileage, not sure what it is, I've not checked, but it sure blew my fuel strategy the first couple trips to the track... had to buy gas once there to get the tank back up to 1/3 full.
With 245/50-16's out back, 50mph is 1800rpm, 70mph is darn handy to 2600rpm, 80mph is 2900rpm.
The car is my daily driver, but it's all city.
4.10's are not bad on the highway, but the 3.73's were definatly nicer for long trips.
Hope that helps.