Correct, I was wrong about the center tap. On the Honda NC50s they have a center tap in the middle of the windings and one single ground. Looking at the treatland 12V windings, it shows clearly in the photo that both the high and the low are going to the ground in two different windings.
But the trailtech uses both high and low leads into the voltage regulator. So you would float the ground and hook both high and low to the regulator along with the floated ground.
haha am I correct on that one?