bigger is better because it doesnt have to spin as much to make the same boost, it can deliver the same volume while doing less work and hence less heat!
I KNOW I'm going to get dumped on by some for saying this, but.....................:
What you stated is absolute gospel - up to a point. There is a "happy place" where blower size, engine size, engine vs. blower R.P.M.s, blower efficiency at said R.P.M., blower generated air temps, boost level, % of parasitic drag, and max H.P. related to the aforesaid all come together creating the most ideal and efficient combo...hence the max torque/H.P. for whatever R.P.M. Too large or small a blower/engine size/RPM ratio and 'nunna that be gunna' happen.
IMO, an 8.3 blower on a 5.4 'motor' doesn't add up to creating said "happy place". It's my unprofessional >opinion< (did I mention this is just my OPINION?), that anything much over a 4.0 blower is 'pushing it' on a 5.4 "efficiency-wise"...at least as it pertains to anything but a "1/4 mile only" car - if then. But, as I said, that's just my unprofessional 'take' on it.
'LOOKS DARNED IMPRESSIVE REGARDLESS, THOUGH! :lol :cheers