That's very weird statement. Every racing engine needs racing fuel to get to the maximum. Even with Evo IX the difference between proper 102 octane racing fuel and stock "Shell V-Power Racing" is around 20 Hp according to a dyno chart I saw few years back.
The problem with real racing engines (S2000, S1600, RRC, R5 etc.) is that with the stock fuel the octane number and exact chemical properties are not guaranteed. Stock engines and their ECUs can cope with variable fuel quality but it's much bigger problem for racing engines. You can not make a laboratory analysis and new mapping for every petrol pump on the road. It's not only about lower power.
There is also a risk of engine damage. For example if You take a petrol on the pump in time when it is being supplied from tanker you get some water into Your tank. There is always water on the bottom of the tanks of petrol pumps unlike in the barrels of racing fuel. When You start filling the tank from tanker You whirl the water which is normally sitting down and it gets in the fuel.
Another point is what Hari stated. How can You say what is a breach of the rule when the stock fuel doesn't have guaranteed properties. How can You check that? Such rule simply doesn't make sense unless there is a single fuel supplier for everybody.
All in all throwing mud on Baumschlager is senseless.
