just remember, the intake manifold was designed for naturally aspirated application in mind, which usually operates under a vacuum.
that said, people still boost them, not just CRZ's but other cars as well, and a few PSI probably won't hurt anything. guys with sprintex superchargers also run no intercooler, but i have yet to hear any major problems with the intake manifold.
just keep in mind, if you drive hard, as in long sprints at full boost, heat soak in hot weather or bad traffic, or run a day at the track, you increase the chance of the intake manifold cracking. i don't think anyone here has experienced a manifold breaking or cracking under pressure yet, but it shouldn't be dismissed either.
also, Golden Eagle makes a L15 aluminum intake manifold which is perfect for turbocharging which was good to some 500 hp or so on Bisi's build. a bit overkill for 5-6 psi, but something to consider as a back up in case you turn up the boost.
'13 CRZ - PWP EX 6MT