David, would you, or in fact anybody be happy to be beaten by somebody on a bike that does not comply with the regulations, if you were technically they have stolen from you the prize money. You, together with everybody else sign a piece of paper stating that your bike complies with the technical spec. It does not have to be an oversize engine, it can be illegal components inside the engine. even cycle parts !. Do people remember when Suzuki, ( Relentless ?) were thrown out of a TT race after a protest resulted in the scrutineers finding a camshaft that was not to the required spec ?. Of course everybody was in denial that they knew about this. I believe the official excuse was that the non spec camshaft had been numbered incorrectly !!!!. perhaps somebody knows more about that one ! Would the scrutineers have picked this up if somebody had not told them what to look for ?