According to the DYNOJET dyno I was using, 74hp with major mods, but no RS bits. Home made ignition rotor, avgas, F3 box. That was my MC28 SS racer in '95. Regularly protested by Yamaha and even protested by Honda

Engine I built with RS250 cylinders running NSR pistons (don't ask why, it was a street bike) made 76hp.

71hp on F3 motor with unleaded.

69hp on 'cheaty' SP spec on avgas. Hi comp with ahem...blueprinted ports.

68hp on 'non-cheaty' SP spec on avgas, but with HRC ignition rotor and bluprinted ports.

64hp stocker with bits bolted on. No engine work. No cheating.

38hp....Paul's NSR250SP MC28 when he first bought it to our workshop in '95. Oh how we laughed. 65hp when it left without HRC card.

I think 80hp would be pretty damn good.

Excellent is a word reserved for 90+hp. Only had the oppertunity to use it once, but that was on a full HRC kitted NX5 at 93hp.