I ran with no air box last year and my old 583 was giving 53BHP at the rear wheel. Basically I cut the air box off where the filter sits, that just leaves the the part that the coils and battery lives in. I then fitted two K&N pod filters, got to say that it sounds awesome watch and listen to
THIS. I'll try and post some photos of my mods. I also fitted some Brisk plugs.