I'm somewhat sceptical of the 'indexing' or rotating the plugs to align the electrode gap in one direction or another. If a given plug in a given hole is off by 330 degrees from the desired direction, and the plug is 'backed-out' by nearly a full turn, does that not mean that the projection into the cylinder head is reduced by nearly one full thread pitch? I would think that making the spark receed might place it outside any stratified mix area and might hurt performance more than it would help.
And if repositioning the spark by the amount of one thread pitch has negligible effect, then why is "aiming" the electrode (the spark is still vertical anyways) claimed to be so benefitial?
DracoFelis 
Threaded Mode
