I've got mine hooked up with the stock resistance wire (and the wire from the starter solonoid) and ballast resistor. When I searched for guidance on how to hook it up, I found conflicting information. One school was that you only use the ballast resistor when it's hooked directly to the 12V. Other info, including the guy I bought it from, said to use the ballast resistor and the resistance wire. Seems to work great that way.