450+ is extremely good.
350-450 is good.
300-350 is worn.
220-300 means it's extremely worn and likely has a very hard time starting.
Lower than that and it won't even compress enough (make enough heat) to ignite Diesel.

MB's official specs are 24-30bar (350-435psi) is normal, 15bar (217psi) minimum. 3bar (43psi) is the maximum variation between high and low results.