I did variation of this upgrade because I wanted to test pre-gen ignitor boxes on my new-gen race bikes to see if there were any performance enhancements to be had from different ignition curves. I chose to use Y-splices into harness so I can switch back & forth between factory '08 new-gen boxes or pre-gen boxes easily. I had spare 2003 ignitor and pigtails from my storage-unit bikes-in-boxes purchase.
First I laid connectors end-to-end with new-gen connector to determine where on harness to Y-splice in.
Then I removed 3-4mm of insulation from existing harness wiring.
Next, tightly wrap end of matching wire from pre-gen pigtail onto harness wire.
Then solder for mechanically strong and electrically conductive joint.
Repeat with remaining wires an wrap with electrical tape.
One master layer of electrical tape to make it neat and reduce damage from shaking and vibration
DONE! Pre-gen ignitor can just barely be squeezed between mounting posts on new-gen fender. You can see connector for new-gen ignitor is right there for easy and quick swapping of ignitor boxes. Don't try using them both at same time!
