No, there are no threads about that I don't think. A larger gap means a larger spark, a larger spark means more heat and a better burn, especially in lean mixtures. The only thing is you can't just increase the spark gap size without effecting timing. More gap means more voltage which means more time for the coil to make the required output to fire the plug, essentially retarding timing.
You have to be careful with gap though. A lot of cars that came with Iridium and Platinum plugs have their coils designed with a shorter tolerance for over-voltage situations and they can die very quickly.
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- Kyle
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