Here is some info On the HI-6.
Whether you're fishing, tubing, or racing across the waves, Crane's HI-6M ignitions will give you reliable performance for years to come. They increase horsepower, rpm, and throttle response by giving you three times more spark-gap energy than other ignitions, and are marine certified. Their built-in rev limiter automatically drops cylinders in firing order to prevent fuel loading, and uses rotary switches to adjust in increments of 100 from 600-9,900 rpm, without the need for chips. Other built-in features include a system problems check with flashing codes for easy problem diagnosis, cross-fire protection and knock sensor input for nitrous oxide, supercharged, and turbo applications, and triggers for distributor or magnetic-pickup crank trigger ignitions. These HI-6M ignitions have six different advance curves tailored for Mercury Marine applications, or a no-advance option for fixed timing. They have a fully potted construction, with Weatherpak connectors for moisture protection and harsh marine environment resistance.