From what I understand jap fuel is 100.
2 points doesn't make a big difference.
The majority of people do not have issues with missfiring.
It is definitely not the fuel, rather the coils.
My PowerFC's base map ran aggressive ign. timing at WOT.
It only made the thing ping its head off, no miss-fires.
However, there is such a thing has a lean missfire. Run the car lean, it will detonate then get to the point where there isn't enough fuel and will begin to missfire.