Not to rain on your parade but Centrifugal Superchargers were the preferred type of forced induction systems on large aircraft engines for about 4 decades-- and these engines operated their entire lives between 1000-3000rpm. The key to the performance of a centrifugal unit is the gear-ratio or ratios the unit uses to spin the compressor (some units where two or three speeds). Since Ripp might have asked for a specific gear ratio in the gearbox from Vortec it is hard to say that you find performance at x rpm hard to believe without knowing more about Ripp's specific setup.