The man to ask is Dodgee. You could try sending him a pm though he never was that comfortable with this style of communication and prefers phone calls. A conversation many years ago with Wayne Doc and myself he says the porting is unchanged though the inlet may be larger to suit the bigger carb. Now another anomaly the parts book shows a 14 fin head which Wayne had and its listed for the M model only and a 15 fin for the S. Another to ask would be PERMS . Pete owns the very pretty S that regularly scores top marks at Conondale classic show n shine. But the guru of Suzuki has to be Doc, if he doesnt know then it didnt happen. best of luck with the investigation.