this is a note from Carlo Vogelsang re: how he did his wiring harness - I don't know if the harness p/n would be the same for your engine code. You need to find out.

Coilpack harness: 1J0971658L ($37 at worldimpex)
Coilpack harness heatshield: 8L9121659 ($44 at worldimpex)

"It's offically for a AWD Golf, but since the ATC engines are basically the same the harness fits perfectly. Install took me about 3-4 hours, getting the pins out of each of the connectors is the hardest part. I've attached
the TSB as well (has all the instructions)."

right click and save the Technical Bulletin

Check out the APR stage 3 dyno results