You cut the plug's electrode "arm" off even with the edge of the "emitter" electrode to increase the exposed spark area. It's the same principle used by Denso and others in their electrode-less plug designs. It should provide a better burn and racers have done this as well indexing their plugs for decades.

The higher octane fuel also makes sense if you've gone to a 10.5:1 compression ratio as it slows the burn to prevent the pre-detonation that is common in higher compressison engines. It also goes hand-in-hand that you'd need more spark for a "slower" burning fuel...