It boosts up the coil, so there is a better and faster spark, no misfires anymore (extreme NA and FI engines use them)
The HI-6 is a multiple spark, capacitive discharge, electronic ignition designed for high performance street, drag racing, oval track, and marine applications The FireBall HI-6 utilizes the latest state-of-the-art technology, and when used with the recommended Crane coil, delivers a spark gap current three times greater than that of competitive systems and almost ten times that of the stock ignition! This high spark gap current produces fast growth of the initial flame kernel and a stable flame front, for greatly increased combustion efficiency. Dyno tests show significant power gains that result