check out this page at Hexus.net. they overclocked a P4 3.2Gz EE to 4.2GZ+! Sweet!
Quote: I wasn’t expecting much overclocking from the Extreme Edition, due to die size, but 4GHz was a genuine surprise, especially at the voltage needed. It’s a shame the voltage mod on the EPoX didn’t quite work, I’d have been showing off at 4.2GHz+.