I have no interest in copying another's inherently flawed design. The intake setup they use, I'm sure, does well at speed as a ramair device, but it's in no way functional for a street bike. I consider use of a filter non-optional on the street.
Another way the use a plenum helps is this:
Using a foam filter, like a PX500 or PX600, allows the air to enter straight, it doesn't turn like when using a paper or cotton based filter to flow through the media. Initially it seems like an advantage, however, because of the orientation of the R3 TBs, air flows straight into the front of the filter, across the tops of the TBs, and onward out the back. What do we know about air flowing across an open face perpendicular to the desired direction of flow?
We know it's the opposite of good, its terrible. I recently watched a 2 hours tuning session with a turbo V-8 motor using a blow through carb setup, they fought it for 1 hour 40 minutes where it would inexplicably swing super lean as boost started to come on. They trouble shot everything, firing order, ignition timing, boost pressure, swapped carbs, tried a different distributor, etc etc until they realized the hat they were using to blow through was causing the air to do exactly that, flow across the venturi instead of smoothly through the venturi. It ran great without the turbo, made good power with the hat disconnected and allowed to breathe naturally aspirated. Engine ran like pure ass until they swapped hats for one that turned the flow 90 degrees to blow directly through the carb, after they identified that, and corrected it, the motor made phenomenal power.