Nick Read

Still in the process of familiarising myself with my engine bay (MY98 WRX) and I'm now onto the induction tract i.e. between the MAF sensor and the compressor inlet. As far as I can see there are 5 side connections to it, working from front to rear:

A fairly large metal pipe joined by rubber hose at each end, which joins to the top of the N/S inlet manifold (looks like there's a plenum chamber there) under an electrical connector - IDLE BYPASS VALVE?

A vacuum hose of some kind that disappears off under the N/S inlet runner of the manifold and I can't see where it connects to. ???

A vacuum hose connecting to the side port of the boost solenoid.

A largish bore pipe for the recirculated charge from the dump valve pipe.

A smaller vacuum hose in the top of the pipe, above the dump valve port, which goes under the dump valve pipe somewhere. ???

So two questions then. Can anyone confirm the ones I've identified so far, and can anyone clue me in on the mystery pipes and where exactly they go. One at least must be an oil breather. Or maybe they both are?