Boost keeps building up to 19.9. No drop off at all. it is a 7.8 inch crank pulley and 2.75 inch blower pulley. Thanks for the props! The change in cubic inches and compression has been a radical success.... great demonstration of how boost doesn't equal power. We are spinning the blower at the same speed, using the same cam, heads, intake, and exhaust, seeing 3 psi less boost and making 275 more hp!