Yep, the wiring going to the mirror lights is very tight, so going the extension route is a good idea. Didn’t know about that when I installed my Tridiums. I have no problem with cutting into wiring and so far so good.

I really don’t ride much at night so I don’t know how much they help. I use them primarily for increased visibility in the day, and I run the fog lights on all the time as they are much more visible.