Streetmaster to Airgap

Yep. On a combo that makes less than 240 whp, 15 hp more at peak is quite a bit IMO. More importantly, it makes at least 15 hp more at EVERY point on the dyno pull. 22 hp more at 3000 rpm. I would imagine that the SM would feel like a complete turd on the bottom end compared to the Air Gap.

Is the demand for air greater at 3000 or 5600 rpm?

That's a difference of 6%