VALVE ASSY, VACUUM SWITCHING, what's this for ?

[parrot]

Yes it is a generic idle up VSV. It will only work if you have a GT spec charge/lights loom and GT spec underdash loom. in other words a functioning idle up circuit.

As you can see, one vacuum line goes to the throttle body to sense when the engine is at idle, the other outlet goes to the airfilter i.e. atmosphere.

Edit: there is another idle up vsv used when the vehicle has aircon which mounts on the right strut tower, at least on RHD cars.