EDIT THIS VIDEO IS OBSOLETE See Part 4b for the best way to wire a Delco EST Ignition Upgrade Kit into the Thunderbolt Five harness on your boat. But for perspective on why Part 4b is better you should still watch this video.

In this video I show detailed steps on how to modify a Mercruiser TB V harness to upgrade the ignition system to a Delco EST Ignition System. Contact me by email if you’d like to purchase my kit.