Overclockers Online has posted a review on the Z4 Waterblock, made by the people from Overclockers Hideout.

Fact that the water is shot in the center of the block when entering it is a very good thing ... because exactly below the center of the block is the cpu core. With the water being aimed at the core, lower temps are achievable compared to blocks were the water enters at one side and leaves at the other.
After the water has hit the center spot of the Z4, it is forced into the maze which guides the water all the way through the block not leaving one dry spot. The water is than pushed out of the block and goes back to the reservoir, after passing through the radiator of course. As the speclist shows, the water goes through a 13.5 long cooling channel ... sweet huh? This design makes optimal use of the entire waterblock and should result in lower temperatures, which again results in higher overclocking results .

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