Turbo Problem?

[Cowboy Dave]

That's interesting to hear that there is enough pressure going through the PCV to make a provent whistle. I guess that explains why my drain hose used to leak oil - the pressure was always going to force it out I guess.

[RHKTriton]

I wouldn't think that you should any significant net pressure in the Catch Can as there is a big "hoover" at the end of the air intake pipe sucking everything away.

Suggests a significant restriction to air/vapour movement through the catch can.

Ultimately the diameter of any plumbing away from the rocker cover opening should be as big (if not slightly larger) and if your doing a long hose run, you should up-size any tubing to minimize flow restriction.