Resistor wire from coil to fuse box...HELP!

Hi guys, I have fitted a polo coupe engine into my mk1 golf and I have been told to up rate the resistor wire from the coil to the fuse box. Unfortunately I am beyond useless at wiring. Can anyone tell me which one it is. I have a white wire, a black wire, and a red and black wire that all go to the fuse box.



This is a picture of my coil. Can anyone tell me which wire I should up rate.

Thanks
james

you only need to do this if you're fitting electronic ignition to the car, you'll also have to change the coil!

the resistor wire is usually white/purple, it will run all the way to the fusebox. its not the red/black, thats your rev counter feed and its not the green thats the points trigger wire