My manual says "no less than 6 bars", which is about 90 PSI. So I set the line pressure at 100 PSI and it worked fine. One note about the compressed air though: If you're not right at TDC for the cylinder you're working on it will turn your engine over! I didn't want to hover on the brink like that so I turned each cylinder just past TDC and put a breaker bar on the crank nut with the handle against the shop floor. So when I pressurized the cylinder it would try to turn in the correct direction and the breaker bar would hold it in place. That worked well.
Experience is something you don't get until just after you need it.