[youngvr4]

The only reason for reducing spark gap is to eliminate misfires. Misfires are usually occuring because the ignition energy produced by the coils and wires is less than what is needed to produce a good spark. Smaller gaps, or smaller electrode tips (like found on platinum- and iridium-tipped plugs), require less energy to spark. So reducing gap to elminate misfires is OK up to a point. After that either the ignition must be made better (more energy) or the cause for increased spark voltage requirements must be dealt with (lower the boost).

For our engines, too large a gap, say over 0.045", should offer no performance advantage. Medium gaps, say 0.034" to 0.043", should be fairly equivalent powerwise. Use the largest gap that also produces the least amount of misfires for your setup. Small gaps, say less than 0.030", may start to hurt combustion a little and lead to poor idle (popping in the exhaust for example) and poor emissions (the spark kernel may now be too small for good initiation of combustion). Use small gaps only in extreme situations (such as the ignition system is maxed out and boost is very high).