Head Porting Recomendation?

After years of being driver/engineer we deal with Critical Velocity in fire hose sizes, as well as the Laminar flow of water. For us the concern was the nominal amount (GPM) of water that we could flow through a given hose size before the efficiency went away. This is to say I could increase the engine pressure but at some point your going to have to deal with the 6 principal's of hydraulics in order to increase Water flow.
From listening to the head porters and gurus in this thread, the obstacles seem quiet similar? I am right?