Whithout wishing to be rude where on earth are you coming from. Listen to Westline.
A diesel engine HAS to make rated rpm plus droop. On an electronic engine droop is only about 50 rpm. Therefore unless you get to rated rpm plus the droop you are overloading your engine.
Bear in mind this is by the exponent of the rpm. Therefore running at WOT and only reaching say 200 rpm less than rated speed can result in an overload of as much as 100%.
Any diesel engine will not be damaged by running on the governor.