@ OP, my bad I didnt see the "e" so I thought you were talking about going from a Q6600 to a Q9550 for example, anyways you have an E6600 which can do 3.2Ghz quite easily maybe even 3.4Ghz depending on the temps.
Yea. I am currently doing 3.1Ghz on my stock cooler. Very smooth and temps are almost the same as stock clocks. I think I can push it to 3.4ghz or even more with a good cooler!