i have a 97 geo tracker with a red neck ram set up and a power steering pump from a jeep with a psc pulley on it. i'm also running a under drive pulley from rocky road and was wondering how much of a differance there would be pump pressure if i swapped back to the stock drive pulley, because there is quite a differance in diameter between the two.
thanks-kevin

well, do this: calculate your stock ratio, then compare to what you got now. just measure the diameter of them to get the ratio, like 4.5inches : 2.3inches.
if that was it, you'd divide the 2.3 by 2.3 to get 1. then divide the other (4.5) by the same 2.3 to get the other x:1.
that's stock. then do it for the setup you got now and see what that turns out to be. the difference in percentage between those two is how much the pressure should change. (approximately of course)
so if you got 20% underdrive from stock, and you go back, that's about a 20% change in pressure too, right?
easy, right?!

in other words, just meaure the percentage change in drive pulleys!

thanks for the help i'll be doing that monday after work