Streetmaster to Airgap

15 hp is a stomping now?
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.