Robo, that Ebay intercooler works fine. The in/out side of it though has tight angles to keep it compact. I'll eventually remove these and fit a funnel like inlet that will curve down toward the turbo and fit the outlet side to the inlet manifold by way of a boltable flange.
I've gone big with the radiator as it was being run behind the cab and out of the main airflow. A friend had a thermo fan setup from the Ford Falcon with a frame made that fitted the GQ radiator. Twin 16" Spal's fitted to a shroud would be interesting! Out front, I couldn't tell you how efficient a heat exchanger of any particular size would be with one of these W2A intercoolers, or any for that matter. Bigger is best though! I didn't want to add another 'radiator' in the front.
When compared with ARE's graph's/test's my system is working very well.