[Kev0607]

Bear in mind that the aux belt isn't a totally silent part either as its in motion. For example, if you start the car & put your head at the wheel arch & listen closely, you can hear the belt moving around on the pulleys... Its a movement/friction noise. Obviously, a rattling pulley would be another noise altogether, but it can be hard to distinguish sounds in that area of the car because you've got moving belts etc too that make a noise as they move.

The ticking/tapping noise in question doesn't sound anywhere near as bad as the video on your channel from about a month ago (I know that injector has since been replaced, but it was a much louder noise than what you're experiencing now).

There doesn't appear to be any leaks now & I'm guessing no codes either? If so, it may be a case of leaving it be for a while to see if the noise gets any worse (Like the sound from the video a month ago). Replacing the rest of the injectors isn't cheap & there's no guarantee that replacement will solve the noise you're hearing now (It might not be the injectors after all).