You're right, I forgot that little word centrifugal in there. Although, the Roots blower is still belt driven off the crank, so it will spin faster and flow more at higher rpm. Wasn't someone pursuing producing a roots type blower for the s2k? I had heard something about it a while back, but nothing recently. Another advantage of turbo over S/C is the ability to change boost level with a boost controller, instead of having to swap pulleys.