Edelbrock offers 91 and 93 calibrations. The only difference being ignition advance at high engine loads.This is a nice kit and I love those curves and the way it brings up the torque curve in the upper rpm to make a nice level flat predictable torque curve. When I saw the Dyno I was worried you could only run 93 octane but looks like the manual says you can run 91 so thats good.