The stock Intel HSF seems to be pretty good, but I wouldn't go over 3.0 GHz with it.
All chips, even those cut from the same wafer, have small differences in performance. For example, my E6600 will run at 3GHz on less than stock voltage. But I cannot reach 3.6 GHz with any reasonable core voltage with my present cooler. I chose the AC cooler not for economy but because I wasn't sure that anything better (larger) would fit in my case. It's really hard to find what we would call "good" cases here. And if you do, they are about twice what they would cost in the U.S. The AC Pro cooler is an excellent "budget" cooler. Next trip back to the U.S., I will pick up something better (larger), such as a Tuniq or something similar. It will fit.
Whatever you decide to use, and how hard you decide to push, watch your CPU temperatures and case ventilation. More fans do not necessarily equal better cooling.