um, nothing........
unless you Need larger or smaller gaps due to a heavily tunned motor.
the std gap is what you should be running, no matter what.
larger gaps make a larger spark but once the mixture is ignited, spark size doesnt make a diff.
turbos might need a smaller gap so that teh spark doesnt get blown out, due to the density of teh charge being to high....i.e. the smaller the gap the more reliable the spark as tehre is less change of it not bridging the gap.
dont worry and dont bother with plug gaps..........
and dont buy super 4s.....they suck poo poo and wont give you any performance gain for teh 100% extra you pay.