This is the sense wire mod. Very easy to do. Got me between .5 and .75 more volts.
You can get a new plug at Auto Parts Fast at RockAuto
Then after I disconnected the negative battery cable, I unplugged the alternator.
I then took the thicker of the 3 wires. This is the one that goes to the larger plug. And I soldered the same sized wire. I used a fused wire just to be safe.
Then I cut off the old plug leaving enough wire on the plug that I can use it again. And I soldered the two other wires to the new plug. Be sure to connect the correct wires.
Then I went under the relay panel and hooked up to the main +12 cable. Ya, I know I didn't have a wire terminal, I'll correct that shortly. This wire is the extra wire on the plug.
All in all, this took very little time, and cost under $10. It can be done for less. At idle I still have about the same 12.7v but driving I was getting between 12.8v and 13.2v, and WOT was getting about 12.7v to 12.9v. After this mod I'm getting about the same at idle, about 13.7v to 13.8v driving, and about 13.4 at WOT.
Here is the difference.
Scan before, note volts.
And this is a scan after adding the sence wire.