Just to be sure I'll bring it up:

R1 carbs being CV type have butterflies in them whereas FCR carbs and others have slides only. The big flow advantage of FCR is that once the slide opens there is nothing in the way i.e. throttle shaft etc.

Motorcycle carbs tend to be a little bit better even CV style, not that DCOE carbs are bad just the bike carbs of the same size seem to flow more.

Tom