We have almost the same setup. I use the same Powerbox spark switch as well. I flew the plane once with a low setting at around 30%. I plan to test tomorrow with a little higher setting of around 50% and will tune to the rich side of peak RPM. The first flight was really short since i had an aileron flutter issue... long story.. but the lower setting on the pump seemed fine, but not a real good test.. I'll let you know.