well you have to being blow through so unmetered air doesnt get into the mani, but i think anyone could do it.
underboost the PCV is forced shut by the mani so boost doesnt get into the crankcase and inlet, but blow by is building in the crankcase because a little will pass the rings. all that blow by then gets forced out of the crankcase and sucked into the inlet by the turbo. when going for power i really dont want that blow by crap going through my inlet and turbo etc. now you could leave the PCV in place but just cap the inlet return and hook that line to a catch can and all would be good. however i like simplicity and while im sure no blow by is being produced under vacuum i still dont like the chance of my mani seeing that crap. before i removed everything from the inlet and stuff i did remove my mani and the heads did have a nasty build up of sticky ass crap. from mile 1 my 2011 wrx will have everything pulled from the intake system so only 100% air gets in.
Scott-2011 WRX 335HP 394TQ 93 VF52!