Due to my bike being 30 years old and having various places where I was having some resistance in the ignition system, I was seeing a voltage drop on the red wire going into the TCI. The was causing an occasional starting problem and also causing a low RPM stumble when riding.
Since then, I have installed a standard relay that takes voltage from the red wire that was going to the TCI on the large connector that now powers the relay and am using a fused wire directly from the battery through the relay to the TCI. This way, when I turn on the ignition, I get about 13 volts to the TCI rather than 10 volts or even less. This has improved my starting greatly and has also eliminated the low RPM stumble I was having occasionally.
Another plus is I was occasionally seeing a voltage drop on the gauge while riding, down to about 12 volts. After installing the relay, I am seeing about 14 volts on the gauge anytime the bike is running, especially above idle and I usually have my idle set about 800 RPM's, which is low for some.
It has also eliminated an occasional problem where the bike would just die while idling and having all the lights on. I assume the TCI was just not getting enough voltage to run.
I did this mod a couple months ago and have yet to see any negatives.
RandyA