i dunno shiet bout gs-rs, but this is what it says in service manual:

"two air intake paths are provided in the intake manifold to allow the selection of the intake path most favorable for a given engine speed. satisfactory power performance is achieved by closing and opening the intake air bypass control valves. high torque at low RPM is achieved when the valves are closed, whereas high power at high RPM is achieved by when [sic] the valves are opened."

valve opens at 5750 rpm and only come on the b18c1, by the way.