"Knowing that airflow is super critical for this little engine, Duttweiler ported the intake and exhaust ports as well as the four-valve combustion chambers. Both Duttweiler and Ford Motor Company engineers agree that short stroke motors don't like a lot of camshaft. Big lift and duration do not work. The gross valve lift is a mere 0.340 inch, but the pair of intake and exhaust valves per cylinder makes up the difference in ultra-high lift all across the entire rpm range. There's nothing else trick in the valvetrain. The valves are stainless steel factory units, and even the valve springs are stock."
I did not discuss the heads with him. This is what the article said...stock valves, valvetrain, cams, ported & Honed. Not sure if/why a different casting..these heads flow very well in flow bench..2.5 better than 3.0 despite smaller valves! There would be room for improvement with the 3L valves too, a must IMO. Tom, IIRC you had upgraded valvetrain??
I'm not critizing you efforts just reponding to your initial comment about out-running turbo V6s. Turbo is the best solution for zetec without a doubt.