General plug theory is that you should run as large a gap as you can without getting blowout. At some point, based on A LOT of factors, the amount of spark you have simply won't be enough to efficiently combust all the fuel/air in the chamber (again, A LOT of factor contribute to this). It might be plug energy, spark length, chamber design, timing, cam-profile, etc... You'll run pig rich, have skyrocketing EGT's, and buck and stuble and hurt things.
Running a higher capacity spark system/coils/computer, could change things enough that you need to completely retune spark and fuel. Even something as easy as plugs/wires/groundingkit could mean there are places in your spark/fuel tables that have room for imrpovement.
In the case of your average MS6 owner running stock spark electrics and basic bolt-ons, a stock spark gap is probably optimal... and that you can find in your owners manual as always.
To gain datapoints, every oil change, increase your gap by .01 and datalog stuff like knock/ignition/AFR/pulsewidth/etc... and see how even the littlest changes in gap can have measurable effects.
I don't know if anybody has done the homework on this engine... but I can bet there are interesting things we can find in. Remember when everybody said your very first mod should be to stretch the coil-springs for better energy transfer to the plug.
