Rick,

Without a flow bench there is no way you can port a head properly. How can you determine where the air flows through the port? They are an essential development tool. You can not only measure flow but map port velocities and measure swirl and tumble.

I agree with the canadian guy. Every ported head should have final checks on a flow bench. As you probably know, flow can be affected by the smallest details. Even if you have already bench developed that head, putting every next one on the bench is surely just good quality assurance. What if the ports do not all flow the same due to a minor detail?

As for pressurised flow, if you look into FD you will find that air does not flow significantly different until your reach very silly pressures.