Wasn't there a recent comparison test between a Boxster S and a new Z4 M roadster? If I remember right, the Boxster S had the better track times but it was noted that the M roadster was much improved. I'm rifling through my magazines, but I can't find it.

It's logical that the Cayman S would outperform the M Coupe, but not by much, probably a gap that could be closed with some mods.