I'm comparing multiple stock bikes with different exhausts. We have run several Brocks pipes, Murray, Muzzy, V&H, Hindle.
Tune for every pipe? In theory, sure. I can tell you from my experience that 12.8 to 13.2 AFR makes no difference in performance at the track. I spent a whole summer with my wideband logger trying to improve on a tune that I got from a similar bike (on a reputable dyno) and did not accomplish anything. It is my go-to tune for a stock Gen-2 with an aftermarket pipe. Put it in and forget it. In theory you should tune every day as the air is different but we know that doesn't happen.
In the end, my opinion is that any given Gen-2 in good running order will perform the same as any other with the same mods. Most single sided street pipes will perform the same as each other, on any of the bikes. Pick the one you like and go with it. I know it is popular to say every bike is different and needs a specific tune just for that bike, (even two identical bikes with the same pipe) but again if we don't tune every day and even during the day as conditions change we never are really spot-on, right? This is one advantage to an aftermarket ECU that has closed loop Lambda correction.