S-Type (X200) V8-4.2L (2005)
Intake Manifold: Description and Operation
Variable Intake System (V.I.S).
The variable intake system consists of a three stage upper intake manifold assembly, two position electronically driven gate valves and an engine
management powertrain control system.
The powertrain control module switches the intake manifold tuning valves between fully open and fully closed at calibrated engine speeds.
The intake manifold efficiency is therefore increased which will also increase the engine torque and engine performance.