We need to be clear about a few things.
The regulator rectifier puts the brakes on the voltage that the charging system puts out. If it fails, you'll see voltage ABOVE 14 volts with the engine revved. 15 volts and more is an example of poorly regulated voltage...
If you had shitty wires going in and out of your stator, the next logical wiring to replace would be the positive and negative wires going in and out of your field coil.
Open their shield, degrease and inspect, and search for flaws and breaks in the wiring covering.
I opened up my stator 5 months after my rewire to find the oil had destroyed the heat shrink around my rewiring and one joint had busted loose.
At 13.5, your bike is running just fine. 13.5 will charge your battery. Not sure why that seems poor to you, but since you're being thorough, do a deep inspection of your field coil wiring.
Drewcifer
PS...as silly as this sounds, have you really cleaned, and I mean with vinegar or brasso, all the contacts on the bike? Loose ones will also create the issue you're describing. Until I soldered in my v reg, it only put out 13.5 too!
