My car has either 2.73 or 3.23 gears from the factory. I am planning on dropping 3.73's in it. How much can I expect to gain in the quarter assuming I can get traction if I am running mid 11's right now? My official best is 11.76 at 113-114 mph, what should I expect, roughly, going to 3.73 with the same motor setup as I had before? The car is an auto.

 

what size stall?

from 3.23s to 3.73s: .08 - .15 depending upon your stall
273 --> 373 .1 - .25

what rpm do you turn? Make sure that you leave enough room including a few hundred rpm for converter slip.