As I have have recently found, In standard form they boost around 5-7psi but when you open the intake and exhaust it flows better cos it has less restriction, so inturn boosts harder.
If you plug a hose straight from your actuator to your intake pressure nipple, whatever that reads is the lowest it can go.
Mine has Cold airbox, FMIC,and Full Exhaust and 12psi is the lowest I can get.
Hope this helps.
Dave