By increasing the pressure of the air column waiting behind the intake valves, it is similar, to a small extent, to super-charging the engine, forcing a larger quantity of air, albeit at the same volume, into the cylinder. This effectively raises the volumetric efficiency of the engine at that point, consequently increasing the power output as well. At the RPM point which the intake runners are tuned for, there will be a maximum volumetric efficiency, and equivalently a maximum power output, with this point aptly termed as the peak power RPM point.