I've run the mallory unilite and MSD 6AL (with their high voltage coil). The box contains power electronics to provide capacitor driven multiple sparks at low to medium rpms. At high rpms there is not time for several sparks so it functions more like a regular high voltage ignition in that realm.

I bought my first one in 1988ish for my '68 427 Vette when its factory transistorized ignition starting getting weak. When I put the MSD in I was sold forever. That Vette came alive down low like it had never done before. It really helps starting and warm-up. When the X wanted to drive it one day I slipped in the 3000 rpm rev limit pill. When she came back she said "something's wrong with the Vette". I said, "What do you mean; you weren't abusing her were you? "

Excellent product and customer support IMO.

Kitz