What's the max RPMs on that supercharger? 14Omm crank with a 50mm pulley pts you at almost 3 to 1. I ran a little over 1 to 1 on my supercharger with my A15 and got 5 psi. That was spinning the SC at around 11000 RPMs at 8000 RPMs on the motor. That was more than enough for the A15 that I built. But it just wasn't fast enough.