Don't read if you're close minded
Funny in the Article they still picked the 750 ultra, the 750/850 ultra made most peak power at lower rpms so at least on top end there more efficient, they didn't really tune the 750 and 850 ultra at the track so who knows how far off they really are, they speculated the 650 would be most streetable.
And in the end they picked 750 ultra and even if the 650 is being more effective with atomization, vaporization and whatever the 750 ultra can't be that far behind since it's putting down similar results without that much effort. So say the 650 is even better at being more effective with atomization, vaporization etc.. (speculation) It really didn't account for much in reality, they still preferred the 750 ultra overall. Not greatest example of proof for the small.