If your engine has no blow by, knocks or rattles and comes back with a healthy compression test result, then there is no reason why you can reliably make 250rwkws and run up to 17psi.
To do this reliably, make sure your fuelling is sorted, inlet temps and coolant/oil temps are not skyrocketing when you are giving it a squirt and make sure the tuning is good. From there, make sure you always have a good sump of quality oil, i recommend Castrol Edge 10W60 and enjoy RB20 goodness for a long time