I'm not very familiar with gears so I have a few questions. First, I just discoverd that my 93 z28 (Manual) has 3.23's. Now I wouldn't mind a bit more acceleration without the sacrifice of alot of gas mileage but what is a good ratio to upgrade to? Also, what are the two differences if the car came with 2.73s or 3.23s if they both run high 13's to mid 14's?

 

3.42's or 4.10's are the usual upgrade. The bigger the gear the more torque the axle will see, but also the higher the rpm will run. 2.73's and 3.23's are close so the only difference would be the little bit of torque difference and maybe the 1mpg difference.

If you want a better take off go to 3.73's or something, since you are a 93 you have a steeper first gear and a .65 6th gear, instead of the rest that have .5 6th. 4.10 might be too steep for a 93.