The OS has more torque and it doesn't rev as high as the Novarossi based engines.

The OS can pull a few teeth taller in terms of gearing because of the increased torque to gain the top end back, but still have a brutal bottom end and mid range.

The Novarossi most likely produces a greater peak HP at maximum revs, but the power delivery is more progressive until that point.

They're so different to drive it's hard to say which is better, they're both competitive engines.

James.