In my experience with the bike stock and just the HRC card you could see about 50-55bhp. My race bike has run on both the std and HRC card. I've fitted a jet kit, open air box and Dogfight pipes and the std card gave 57 bhp.

Sliping in the HRC card saw 59.5.

Not a huge increase and how Luke F laughed, (his 21 hit 61bhp) but the shape of the power curve changed. It made more power earlier in the rev range, but also dropped off sooner.

Now this all happened in the distant past, before kids and sleepless nights dulled the brain function, so the figures may not be deadly acurate. But in my experience the HRC card wasn't the big increase in power I'd first hoped for.

All said and done my first 40bhp MC28 still whooped my mates around Donnington GP circuit. (that's with the Loop).

Ah......happy dayz