This is taken from an article in the Greeves mag Leading Link No 49 Dec 1992 by Andrew King who is an expert in Greeves "The alloy cylinder head .The head with the off-set squish area is definately a TES item.ie.trials.The squish area should face the front.There is no truth at all in the theory of plug to rear for scrambles. This is pure baloney!.The scrambler has the full ,symetrical,hemisperical head."