Not the expert, but I understand the original Ignitor is similar to the Mopar box, i.e. it requires a ballast resistor (or coil w/ internal resistance). The Ignitor II is similar to the GM HEI module and requires no ballast. I recall it can trigger a better E-core coil like Holley or a Mopar Magnum coil. I recall that Ignitor III adds MSD.