BAD4DR

There is no one answer.
If you're running a T3/T04E 60 trim, with a Stage one, or small F series exhaust turbine, it's likely to be 10-12 psi tops.
Running a straight T3, like a Super 60, it's probably closer to 20+.
On a small turbo, rated at 200 - 250 hp or so, it's likely to be 32+ psi at the turbo outlet, maintaining 20+ at the intake.....

How much will it take? Well, it's generally accepted, that if it's tuned properly, about 300 hp, with a 7500 RPM redline. Getting a wider powerband would be the real key, as almost every Honda I've seen has a curve that rises to redline. It helps to know trans ratios, shift points, and where it's going to fall to. That allows you to develop a setup that makes more useable power. This is why I was very rarely worried about Honda's when I drove my SRT-4. As the nice gentleman in the RSX pushing 300 hp said - "I was almost even with him when it let go....." His reference was to a fellow SRT I knew, that was very equal with mine in track times. And, my street tires hooked up better than his. Granted, the RSX is not a Civic, but it is a K-series, making 30+ hp more than that SRT was, and the RSX is lighter than the SRT. Not to mention, the RSX-S has a 6-speed, with a 5:1+ Final Drive.....

Seriously dude, a safe # for most on a B20, is a T3/T04E at 12 psi.
If you're serious about it, you could make sure you have a good intercooler, good cast turbo manifold, meth injection, a slightly undersized series of the T3/T04E, like the 50 trim, with a .63 A/R Stage3 Exhaust, and put down 20+ psi without any problems.... Of course, the curve will look horrible, but it'll have a lot of boost, and great peak #'s....