Just got my copy of Evo mag and they tested the Cup, 172 and V6 around Bedford Autodrome, the lap times where most suprising with the Cup beating the V6 and the std 172 giving the V6 a damn close run for its money. Lap times were:
Cup 1.26.30
V6 1.28.45
172 1.28.85
Most off this they say was down to the V6 being somewhat nervous arounf the bends, although they did say that it was not noticably quicker than the cup down the straights.