yeah this is where my knowledge falls short, i talked to the guy who designed the stators at harley about this stuff and he said they design the core using FEA software but obviously coils pre-date computers by a few hundred years so some smart fuckers knew how to do the core design without fancy pants computer tools and there are rules for it.
the single ended pickup coil thing is weird too... so the magnets pass and its pulling on the core with a N-S (say, i dunno) then the magnet switches and it goes S-N.... but its not push-pull like it is with a power coil because its only seeing one side of the magnet. the flux happens from changing direction, so i think a wider tab would change direction faster all else being equal because the magnets are covering a bigger distance in the same RPM?
i dunno i'm just thinking out loud, either way all signs point to the bigger core generating more juice which has the ability to fry shit including the ultra fine wire the coil is wound with. the more power coming out of the coil the faster it charges the capacitor in the r-c network on the input side and the sooner your cdi triggers so that explains the timing shift.
its also weird it has that little fork in it? what an odd design feature.