[shelby987]

From my crude understanding, it is based off of the capability of the computer, the size of the injectors (lbs/hr), I seem to remember reading that once the injector is pushing more than 60-70% of its max it actually becomes less efficient at fuel dispersion. Also, the throttle body blades themselves are different sizes (bigger engine, more cfm).
Likely, the designation is more for general guidelines....to base it off of cfm is not the best method, because most people will tend to lean toward bigger is better, and thats not how a fuel injection system works, it reads everything, and then makes the correct decision on how much fuel to deliver....i always thought of tbi as a smart carb, but my buddy prefers toilet bowl injection (step on the gas, and hear it flush)