I have the Radium VTE setup as well, though I did upgrade the exhaust side to AN10 fittings and hose. Also, the fittings into the valve covers are AN10 for the exhaust, and AN6 for the intake. I removed the oem PCV valve, and am using the Radium PCV valve right on the left-side catch-can.
I figure it works as follows ...
Under idle or no-boost the intake chamber is under vacuum. So it draws from the intake valve cover via the PCV valve, but it's not a huge draw. Enough to ensure the crankcase area can't build up pressure. The exhaust side is also pulling.
Under boost the intake-side is out of the equation - the PCV valve is closed so nothing goes through there. The exhaust side however sees a significant vacuum draw from the intake pipe. That with the AN10 sizing ensures that crankcase area doesn't build up pressure.
The catch-cans will do a good job of separating oil from the vapors.
Some will get through to the intake, but not enough to worry about. NOTE I say
will - I'm still working on the VVTi head and going-single conversion. If it looks like too much oil going through, I have information on using proper air-oil separators
Radium makes (as usual) a gorgeous one
Air oil separating system
www.radiumauto.com
IAG makes them, but they're kind of big - this is used to demo in the video above
IAG Performance Air Oil Separators (AOS) for Subaru WRX, STI, Forester XT and Legacy GT
www.iagperformance.com
And BMW has one, but ugh, plastic
BMW Crankcase Vent Valve - OE Supplier 11617501566
www.fcpeuro.com
