At 20 psi I was pulling the crank pulley hard enough to scuff the crank snout from the movement of the crank pulley even with an ARP bolt in there . It was with a Procharger though on an 8 rib with a very tight belt .I investigated machining my crankshaft for a 2nd keyway at the start of my build. I'm running 15 psi with my Saleen. After discussing it with several shops all agreed at my HP/boost level is wasn't necessary so I abondoned the idea.