Please consider that the tempest has to be ooverclocked to the max safe limit as far as a manufacturuer is concerned - EPUK has to warrant it's products.
So there probs is more in the tank as far as overclocking goes.
I have not seen anyone get 3.2Ghz with an X2 4400 using mach2 cooling.
3ghz is possible with both chips - Dazboots got a good clock with his, but that was using extreme settings to achieve this and should be considered exceptional rather than the norm.