[Paul Neal]

As power/performance increases, the "pulse width" (the amount of time the injector is injecting fuel) needs to be made larger. The options, then, are "small" injector with a "large" pulse width; or a "large" injector with a "small" pulse width. It relates to the efficiency of the injector, which as I understand it drops off as you continue to increase pulse width. The use of larger injectors allows the user to keep the injectors in their "sweet spot".