is he not referring to the fact that on the kit the positive will be red and the negative black and on the car the positive is a kinds pink/red colour and the negative is brown, i had this same oh **** moment when i was fitting my kit and i reffered to google to
help me out as i didnt want to plug it in the wrong way, the kit comes with spade connectors that just clip into the existing wiring. make sure you test them before cutting the hole in the plastic cover