I spoke with Darrel Olson ( HPD ) about the scramber 500's head and he was very informative. He had told me that the head was designed to have a sort of duel exhaust perhaps like in the Honda 400ex but there was a last minute change. He told me the head on the 500 is a piece of S**T and ther is much room for improvement. First there is a huge lump in the exhaust port which hinders escaping exhaust gas, then there is uneven cooling of the entire head which creates hot spots and finally the valves will hit the piston if more agressive cam porfiles are used. He told me that he worked the existing head over and it offers a lot of hidden power but the cost is relatively too high. He is currently reserching the feasability of making an aftermarket head. Perhaps future scramlbers will have either duel exhaust or a redesigned head that is backward compatible with previous 500's