Don't forget, it pulls some boost whenever there is KR. Nice added safety feature.
I know on my car, it is impossible to go over 17-18psi without the solenoid. Currently the wastegate rod is set for about 13psi which gives me about 18psi with the solenoid. Not a truly linear adjustment though because the solenoid will bleed more air at higher boost levels, so with the wastegate rod adjusted for 16 I would get more than 21psi.
Just think about letting the air out of a tire, it comes out way faster when you have 35psi than it does when you only have 10psi.