Alright let me help you out....
In case you havent noticed the fueling on the ZX6R is pretty damn good already..
Doing the wire jumper mod actually just lets the bike use what should be there already, (Euro spec)
So now we get into does the US bike have different mapping or not?
No clue...would it make a difference? most likely not..
After the wire mod is done the bikes do the same thing..
Getting a PCIII is for tuning when you mod your bike and you should be getting a custom tune for your specific set-up.
But of course you are looking at $300-450.00 so it is not going to be something you see or can touch..yet will make the fueling spot on..
The tune i had done on my bike is the most precise out of any bike i have ever ridden, and better then my modded RC51,friends TL,GSXR,Busa,ZX10,aprillia
So to get to the simple answer get your bike dyno tuned if you buy a PCIII, AFTER you get the exhaust and whatever else you decide to do which is limited on this bike anyways...
air filter,exhaust,degree cams,cusomt tune....some have played with the ignition some but not sure on the results..thats also with the Race ECU..Hope this helps