The increased output of the 20 Amp Pro-Mag was born of racers being racers; always asking for more power. This stemmed from drag racers that were using a 12 Amp system, but just didn't require a 44 Amp system. The engineers at MSD found that with a few changes to the internals of the generator it would deliver the increased current through the same Electronic Points Box, PN 8106.
There are three different generators available; a band clamp design in both CW and CCW rotation, plus a model built on a Chevy distributor base. All three require the PN 8106 Electronic Points Box. The band clamp versions are equipped with a large Ford style cap while the Chevy version uses a 4-inch cap and both are topped with heavy duty retainers.