General rule is 800 to 1000 rpm below max tq rpm. If its 5400 like my S/B is start with the 4500 as the other poster said, but you may need to go rigth up to 5400 chip to get the most out of the combo. It depands a lot on the cam and wght of the car. My heads are too big for my combo (its what i had) so i run a 5400 stall converter with a 5400 chip to get the most concisten e/t and 60'. Test and tune & have chips from 4200 - 5600 and see what they do. remember more flash (lower rpm chip to max tq rpm) you may start getting the wheels up high. Good luck.