That flywheel of Steve's looks familiar
You can't buy those flywheels. They were made by Endurance Racing for HRC and only available to people "in the know". It's for a MC28 and was developed for the Asian Championship when rules said we could alter the ignition system. I had one fitted (maybe even that one
) and it sure made the engine "BING". Then I made an alloy one that had more "BINGage" than the HRC version and saw 69hp on an otherwise (blue printed) SP spec motor. Worth their weight (or lack of it) if you're racing.
Endurance even made one for the F3. Obviously a lot smaller and lighter, and a lot "BINGier" that the one in Steve's picture.