I wouldn't say the injectors will flow more with the P&H board, but you will definitely have better, more precise control over them. Adding resistors to low impedance solenoids decreased their reaction time. The P&H board, on the other hand, controls these injectors as they were designed to be controlled; with a PWM current limiting routine.

This negative aspect about the resistors would probably be most noticeable at idle with large injectors. Sluggish reaction times would spell a very rough idle. I don't think you necessarily have this problem now.