Ballast

I'm with 67Dart273, Not using a ballast resistor will likely cause an early coil and /or ECU failure and you loose the cold temperature start boost when the battery voltage is really down.

The correct value of ballast resistor for the Chrysler ECU systems is 1.2 ohms. The GM HEI type systems don't use a separate ballast resistor but do have an electronic circuit mechanism to limit the final ramp up current value to the coil. For those who are electronically inclined look up the Motorola MC3334 data sheet on line for an explanation of this circuit. The GM HEI system was based on the MC3334.

In any of these systems it's a fairly safe bet to assume they were designed by competent engineers and tested extensively before being put into production on millions of vehicles. I would tread very lightly on second guessing what was done on these systems and making changes.