Just a note. The PCV should be shut when the engine is under heavy load (WOT) because there low vacuum. If the throttle body blade is wide open the difference in vacuum pressure before and after the blade is vary small which lets the PCV shut and there is no positive airflow through the crankcase.
ZZP's tiny groove should work because there is not increased flow through the crankcase at WOT, there is less airflow or none.