At what pressure should the BOV creep open?

[UrS4boy]

stock BPV is "pull" type based on vacuum not "Push" type based on preload internal spring.if you installed wih wrong orientation,it became push type.

But there is still a spring that keeps the BPV diaphragm closed until a certain vacuum is reached.

[newsh]

The small bore pipe definitely keeps the valve closed.

The pipe opposite the small bore one should go to the MAF hose (the other way round to a BOV)

[Thecrispynoodle]

The small bore pipe definitely keeps the valve closed.

The pipe opposite the small bore one should go to the MAF hose (the other way round to a BOV)

Correct, it's not excessive boost that pushed the bpv open it's the vacuum on the other side of the now closed throttle plate that pulls it open. A vacuum leak or tear in the bpv will hence compromise this.