Looking to add to a discussion on airflow. I think some well-established information on head design, valve angle, and flow characteristics should be considered and researched. The evolution of the Chevy small block to today’s LS based motors is a good example.
A flow velocity applied to a race engine head, especially a NASCAR head with an optimal valve angle and intake port shape, is not necessarily compatible with a Buick V6 production head or likely an aftermarket Buick head(I don’t own an aftermarket head, so I am guessing). I would think this is even more of a consideration when comparing an NA race motor architecture to a production based Buick turbo motor architecture. Parameters for a well designed race engine head, developed on a test stand with analytic tools that the rocket scientist of the 60s could only dream of, is not necessarily going to work on a production Buick motor. The millisecond you end up with flow separation in the intake port, you will lose your ram effect benefit and will not be able to recover the port velocity as cylinder pressure/mass flow(i.e. Improved volumetric efficiency). Some experimental data would be required for Buick head to determine optimal port velocity. The short side radius is usually the limiting feature, but I am guessing the valve seats are also important when the valve is full open(the seats are definitely important when the valve is just opening or closing). As long as the boundary layer stays attached(it is likely a turbulent boundary layer, do not confuse laminar flow with a laminar or turbulent boundary layer), and the surface is reasonably smooth so that you don’t lose too much energy due to friction, you can recover the velocity as pressure in the cylinder. Runner length/velocity tuning will determine the RPM at which the ram effect will be maximum. If you cannot recover the velocity(flow velocity exceeds the port capability to maintain an attached boundary layer), you have also just increased your pumping loses. So optimal velocity on a well designed racing head is not going to be the same for a production head unless the production head is the same as the race head. If you get anywhere near critical velocity, which I would not expect, that is a different discussion.
A note on pumping loses. If you could keep your crank case at absolute vacuum on your intake stroke the pumping loses would be zero. Since this is not the case, increasing pressure drop to the cylinder on the intake stroke means the piston has to work harder to displace the air in the crank case, thereby increasing pumping loses. If you cannot recover the port/runner velocity horsepower will be lost. Vacuum pumps or dry sump oiling can reduce crank case pressure and improve horsepower. On a boosted engine, intake pressure above crankcase pressure will drive the piston down, giving a pumping benefit. The intake stroke does note suck air in, there is no such thing as suction. The high pressure side is always the driver not the low pressure side.
On an NA motor, a tuned header can transiently drop the exhaust exit pressure below atmospheric(intake) pressure to scavenge the cylinder, for a certain RPM range. Not sure if this helps pumping loses that much, but it improves cylinder filling so it improves volumetric efficiency.
On a turbo motor with high back pressure in the exhaust, the pumping loses are high on the exhaust stroke, and obviously increase with increased in back pressure. Cylinder fill will also suffer from back pressure. A different turbine design can lower back pressure at the sacrifice of spool time. If you can lower back pressure to below intake pressure, cylinder fill improves, and you are now using exhaust energy to apply power to the crankshaft on the intake stroke while minimizing exhaust stoke pumping loss. You are now really making good use of wasted exhaust energy by not only compressing air(increasing mass flow), but also getting a net pumping gain through using the exhaust energy and by getting a completely clean intake charge(improved use of the heating value of the fuel).
I think you have two main things to look at for making power, the overall mass flow through the engine and the heating value of the fuel vs the energy value of the exhaust exiting the engine after the turbo/waste gate combined. If you increase mass flow, you can increase power. If for a given heating value of the fuel consumed, you can reduce the energy in the exhaust flow with the turbine you can make more power. The challenge is the power quality and the response time to make that power.
I would bet a paycheck that on a turbo motor, minimizing pressure drop on the heads is more important than intake port velocity. Maximizing the compressor/turbine combination for a given engine will outweigh other considerations so long as the head/cam design is correct for the turbo mass flow capability. With a NA motor the desire is to maximize volumetric efficiency at atmospheric conditions, a turbo motor does not have the same constraints, the turbo motor can alter compressor and turbine to match a particular engine and get the most out of it.