if you get a headlight with the wiring on it, it should be plug and play, as the wires that connect to the ballast and bulb are typically included with used units on eBay and similar, I don’t know as much about forester but on the Impreza and WRX it is plug and play, I didn’t change any wiring on mine (2007) when converting besides unplugging the DRL module (which won’t be a problem for you).