My 2006 FZ6 was running slightly lean after modding the airbox and gutting the cat.
I pulled the plugs after 3k miles and they had traces of white on the elements.
(black = rich, brown = perfect, white= lean)
I believe the factory runs them a little lean for MPG and emissions.
The PCIII is a handy gizmo and gives the user some flexibility in fuel/air ratio's.
Is it needed? No.
If you get one, is a custom map needed? No.
The map I currently run gives me very solid mid range.
I prefer this because the bike does not SUDDENLY hit the powerband in mid corner.
Just smooth predictable power across a wide rpm range.
I would like to add the module that lets me switch maps on the fly.
One map for peak power.
Another map for mid range.
Then a map for MPG.
