Yeah you right , Babbit have same parts number for RZR and RZR S cam, but if you look on 2009 RZR S they have listed HO cam. That's the one I was referring to. Not sure, if is mistake on the parts fiche for 2010 or they for strange reason put reg RZR cam on S.I have a 2010 RZR and when I look up the RZR S cam for 2010 they are the same part number.