I have now a little update. My 4770k is running at 4.5 ghz at 60 degrees C with 1.295 volts, after 12 hours of prime 95. I put some Coollab Liquid Ultra between the die and the heatspreader. Comparing to my Noctua TIM it didn't do anything really, but after 3-4 hours of lapping the IHS, it has gone really stable. I can now see all cores running the same temperatures. Even with CLP ultra it wasn't totaly stable, core 2 and 3 was running considerably hotter than the others, but now they are running the same temps and is running everything stable.
Stock: 4.2 ghz at 88-90 degrees
Delid with Noctua NT-H1: 4.4 ghz at 65 degrees with different temps on the cores
Delid with CLP Ultra: 4.4 ghz at 64 degrees with different temps on the cores
Delid and Lapped IHS: 4.5 ghz at 60 degrees with same temps on the cores
My IHS was really warped, after 2.5 hours of lapping, there was still a little nickel left on the bottom part and center of the IHS (I've done plenty lapping of Core2Duo's and Core2Quads back when they where having problems, so i knew how to do it), but i ended up with a nice mat finish and i am really happy with the result. Wondering what next years generation will bring. If they make a really good overclocker then i might upgrade then