Its a bad idea to mess with the PCV system for several reasons.
1) The driving force for succesfully keeping the crankcase under a vacuum is very low. Adding a catch can into the path between the crank case and the throttle body increases these losses.
2) The engine management system actually accounts for some oil vapor coming into the intake. This is important because that oil vapor affects the overall octane of the air/fuel in the combustion chamber. (This is true of an EGR (Exhaust Gas Return Valve) when not under boost as well)
3) Failure to maintain a vacuum on the crankcase causes pressure to build on the wrong side of the piston rings. This can affect horsepower and in extreme cases impact the rings ability to seat properly. This in turn increases blowby and makes original problem of too little crankcase vacuum worse.
4) Ironically, for the PCV system to work as designed, it also relies on the restriction of the OEM air filter. Under boost, that restriction insures that the hose at the turbo inlet has vacuum to pull from the crankcase. But, eh, thats the first thing people mess with not realizing that they have affected the lifespan of the rings and increased the risk of leaky gaskets all over the engine.
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