Injector coding. L322 Really necessary?

Hi, I changed a couple of injectors last year as the motor was running a little rough and had high spillage rates, since then whilst the motor runs fine it does sound a little more tappety than before and I had planned on replacing the hydraulic lifters at some point thinking maybe they were past their best. However whilst looking at RAVE last night I noticed it calls for the injectors to be re calibrated with T4/ Testbook when replaced, could miss calibration be the cause of my tappet noise and is there anyone in the Birmingham area who has the gear to do the job for me? Would much rather pay a forum user than the stealer.
Many Thanks.

If it's a Ford diesel engine, the injectors have to be coded.