MSD 6AL Wiring and Ballast

Some comments:

If I was using MSD, I would carefully strip out the un-needed wires from the old ECU. Then you can tie the IGN1 (run) and IGN2 (bypass) wires together and run tie those to the MSD "small red."

BE CAREFUL not to cut loose any splice with the "run" wire as this supplies VR and alternator field, and maybe choke and smog goodies
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NOW:

YOU DO NOT NEED to remove the ballast!!!!! YOU CAN ACTUALLY take the factory stock wiring and do the following:

Hook up the large red/ large black as instructed

Then take the OLD coil + wire and tie that to the MSD small red, LEAVING the ballast in place. IT WILL WORK JUST FINE

Why? Why does it? Because the small red is a low current trigger wire, and because it is low current, it does not draw very much off the old ballast wiring.

If you think you want to leave the old wiring intact in case of an MSD failure, this will work fine