Like what Miggs pointed out, it's basic physics, least resistance, period. Unless your sparkplug has multiple spark tips (not the conductor tip), iisa lang labasan ng kuryente. Your "electric bolt" will not split into two if you use a V tip, it will not split into 4 if you use a 4tip, it goes to the ONE with the least resistance.

Mas lumalaki ngang chance mag misfire if you have multiple conducting tips since the current won't go straight to a designated tip eh, maghahanap pa yun between the "choices" that are available..

Gains on a stock engine? One word... PLACEBO.