Higher injection pressure results in retarded firing timing but better atomisation. Its a delicate balance.
In all cases all injectors should be within 5% of their injection pressure after being run for 5000 kms after new nozzle work (this is achievable if the proper way in the service manual is followed)
An engine with mismatched pressure nozzles will cause severely poor running along with damage to the engine crank and timing geartrain on 1kz in the long run.
Tl dr
Dont ever cheap out on the diesel pump and nozzles, it will bite you like a kashmiri viper!