This is Dave's current system. He is not entirely happy
with the water cooling.
Air flows through the inter cooler on the left side and the oil
cooler on the right side and then through the 2 inch thick rad
mounted below the engine and out the exit below the cowl.
The air is also heated by passing over the turbo charger
and exhaust manifold before it flows through the rad.

Does anybody have any suggestions what Dave could to to improve
the water cooling?

Oil cooling and inter cooling are fine.