[hara]

In my opinion, with this design, drilling further into the WW block will not improve performance but will F- it up.

The reason is that you're messing with the fin to channel ratio. By making the fins thinner you're increasing the thermal gradient A ~1/deltat

But then again, you are increasing turbulance, reducing the boundary layer, increasing the heat transfered to the water.

In the end the lost performance from this mod outweighs the gains.

This is a similar design by a friend of mine:

http://forums.procooling.com/vbb/sho...&threadid=6164