Airflow to Cubic Inches

"Potential" and "lower than it can be" are relative terms. If the ports is too small it peaks earlier. If the port is to big it peaks later so you would have to rev it higher. The issue here is where do you want peak rpm. If you want it to peak at 6k then you would pick a head, cam, manifold etc that will work. If the cam and manifold are sized for 6k but the port isnt then its not going to work quite as well. How well it works or doesnt depends on how far off the mis-match is.