Someone nearby asked me for help not long ago. He came over and I hooked up VCDS and saw it wasn't making boost. I looked under the hood and his EVAP to valve cover wasn't connected, but that obviously wasn't the cause of boost loss. He mentioned he just had the PCV replaced and I noticed the new PCV had white print on it from its manufacturer...so obviously not OEM. I disconnected the tube at the intake manifold and blew in to it and it did not hold pressure. This suggests the check valve in the PCV isn't holding the pressure or the tube itself his leaking due to a crack or poor o-rings at the ends. He just contacted me to ask if I would help him install the new OEM PCV he expects to arrive soon, I know...too easy, but I said I would. We'll see if that is all that is wrong as boost issues can and are sometimes not just due to one source. He also had a leaking fmic pipe connection on the hot side and I gave him a new o-ring/seal to fix that. But not sure if he ever did so.
The PCV was revised and there once was an "open campaign" to replace them here in the states. The change went from both check valves in the PCV and none in the rear breather...to...one check valve in the PCV and the other inside the rear breather tube. So, with the revised PCV, one should also use the revised breather tube.
This is the revised PCV with one check valve at the intake manifold connection, and the other was removed from the circled area and put into the rear breather tube;
So, if anyone goes to install a PCV that is void of the check valve at the circled post-hole, you should also make sure the rear breather has a check valve. The rear breather valve will shut when the engine is under vacuum and open under pressure. The intake side check valve will open under vacuum and close under pressure.