I didn't realize the price difference was so big between them, but sure enough $4800 gap; really is almost the price of the setup.
Forced Induction busas have no 2 wheel speed peer, never have, not news lol.
Rocket 3s have no peer with the same/similar riding position.
As for the original post, didn't seem like a complaint, but instead an inquiry as to why the R3 doesn't see the gains the Hayabusa does.
Simple answer is RPM, sure one could talk about cam specs, pumping losses, parasitic losses of heavier components, shaft drives, chamber shapes, head flow, 4 vs 3 cylinders, piston design, rod ratio, etc but in the end it all boils down to RPM.
Even simpler answer:
Horsepower = Torque x RPM / 5,252
It could be easily argued that the Rocket has a much larger gain than the Busa:
268lbft/144lbft = ~86% gain
190lbft/110lbft = ~72% gain