Tony, I am a Design Judge, not a Cost Judge, so I just don't know.

But remember "Speed costs money, how fast do you want to spend'?

However, fridge magnets are cheap and plasticky, so I guess they are probably multi polarised, ore even worse, circularly polarised. Certainly, fridge magnets are made from amplified ionic chinesium ore.

To use that sort of magnet will cause those wobbly electrons to enter a circular motion so all actual current flow will stall. If this happens at speed and the driver doesn't de-clutch immediately and allow the engine to stall, the electron pressure build-up would be very dangerous!

Maybe the secrecy that surrounds this subject is because of the dangers of people using cheap chinesium or improperly polarised magnets. The downside is that this hides the terrific performance advantages from many beginning teams.

But again, I advise those beginner teams to be careful if you act on what you read in forums, because I have seen some very inaccurate stuff!

C'est la vie!