Josh P,

The .85 ohm resistor that comes with the MSD Blaster II coil works well. The MSD coil and resistor will bring up the coil voltage from (stock system) 6 volts at a 600 rpm idle up to 10 volts. Idling for hours in traffic was greatly improved.
I ran this set up for about 5 years with the NGK plugs gaped at .045.

This past year I switched to the 3 ohm Pertronix HEI 60,000 volt coil with the MOPAR orange box. The coil now shows a full 12 volts at a 600 rpm idle. The engine never misses a beat and is the steadiest idle I have heard from any SL6. With the Pertronix HEI coil you do not need to run a ballast resistor.
The Pertronix engineers have assured me that this is the best set up for the MOPAR ECU providing maximum voltage and spark and is comparable to the Ignitor II system.

The Ignitor III system is the best to date and you can run any of the new coils that are .5 to .7 ohms for maximum spark, primarily for racing. The 8 cylinder version has been released however, the 6 cylinder version is still in work.

Click on the red link below my name to view pictures of the 3 ohm coil.