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I normally use 2-3 bar. My cylinders start moving at around 0.2 bar.
Well printed cylinders (no underextrusion, good straight walls etc) have only very minimal air leakage. Nothing to worry about because the air consumption during normal operation of the cylinder is much, much higher. You can always do post-processing (varnish etc) to reduce leakages further, but I don't care about that.