Here are some replies I got from a Honda forum I visit when I inquired about effects of boost on vacuum lines. (Yes, I own a Civic too)
"The stock brake booster has a one-way valve in the line so it won't see any boost.
The
fuel pressure regulator works fine for boost and continues it's 1:1 pressure rise.
Evap purge is only actuated at certain times which I assume is somewhere in vacuum and low throttle.
The map sensor also can work as long as the voltage output is limited to keep the ecu happy (like in the hack or using a missing link). It's usable to around 11psi. cruise control. i just know that it still works. It's weird when you fall asleep and the bov wakes you up at the top of a hill....i bet."
"The brake booster has a bit of a reservoir for vacuum. Ever notice when you remove the booster line it sucks air in for a few seconds."
"Yeah, it is designed as a saftey feature to give you one.. maybe two good pumps before your brake assits runs out. It is for "emergency" use if the motor dies while driving."