the guy at the speed shop told me i didnt need a ballast resistor so i took it off havent had any problems yet. I got mine for $201 canadian so if you have a shop in your area that can source one for you it will save the s/h. Im not sure of the gauge
of the wire but just test the + wire that goes to the coil + teminal to make sure its a constant 12 volt source. if that passes muster then just splice in the plug you get from the junkyard hei and hook it up.
its worth the extra 50 or 60 bucks if you plan on building more hp as it will take the rpm better than a stock unit