Flow numbers and max HP potential

With the 0.26 thing, I don't know where they came up with that, and what all went into the calculation (factors, assumptions, etc) to boil it down to 0.26....but, it happens to be fairly close for my car. My heads flow 293 @ 0.600 on the intake, I have a cam that takes advantage of that lift (about .630 lift)...by my best guestimate from the drag strip, my car makes close to 600hp, depending on parasitic loss and such.

I think the calculators are nice to give you a ball park estimate, but a savvy engine builder could probably push those limits past the theoretical.