Not sure of max pressures, but with the 'half a hole method' you should have around 7psi with a -31 and around 14psi with a -34.
These can be increased slightly by a tad more preload, probably to around 10psi with the -31 and 18psi with the -34.

You could just keep winding the actuator in until you see the max, but thats not really the way the system is supposed to work. you end up with a harsh wasegate actuation or worse.
The normal way for example is:

If you wanted 20psi for example. You could use a -31 with a tad more preload at 10psi and the BLEED 10psi away, or a -34 with a tad more preload and BLEED 2psi away.

basically you shouldn't be looking to run the max boost over the pressure rating of the actuator itself.