Yeah that's a tough one to measure exactly. It's more subjective. If it's obvious you would know. Or ask your wife if she sees any difference in the tailpipes without saying what you are looking for. If the answer is "this side is much dirtier than the other" than I'd have it checked out. You could also thoroughly clean both tailpipes as a baseline and monitor the sooting for evenness over time.

And to ease your worries about bore scoring, I had an engine tapping sound in the rear lower passenger's side area. I was worried about it coming from bank 2, the bore scoring more common bank. I was actually hoping it was "only" a lifter problem as the repair is a whole lot less than cylinder work. My local indy with a $8 mechanic's stethoscope narrowed it down to the tandem oil pump as the loudest area of tapping. I replaced it via DIY, something like a $200 part, but the tapping is gone. Mind you this is a 997.1 but you get the idea - not all engine noises are bore scoring. But noises that get louder over time should not be ignored.