I was running 18psi on it for a while without any issues. I would imagine that it can hold quite a bit, say over 20psi. The only thing is that you need to make sure that the vacuum lines are properly tie strapped on the IM or they will blow off.
I ran 22psi through it a few times and the only issue I had was the vacuum hoses popping off. If it keeps happening I might cut and drill them off and put some brass barbs at the back, but till then zip-ties plus zip tie gun FTW.