The operating range means what RPM range your engine is built to run at. This intake is setup to accommodate flow up to 5500rpm. Past that, you will be maxing out its flow capability and yes, your power curve can drop after that. On the flip side, their intake built to handle high RPM use will do the opposite. You will sacrifice some low end for top end flow. It will come down to cam/head combos and such as to the operating range of your engine.