I built my own pressure bleeder and the instructions said to not go over 14psi. I didn't want to have to crawl out from under the car so many times so I figured 20psi would give me a longer interval, plus maybe drive the old fluid out with a little more force taking more crud with it.

While under the car I noticed fluid dripping out near the engine bay and I found that the rubber grommets that fit the reservoir to the master cylinder cannot take that kind of pressure without leaking.

Lesson learned.