I will tell you trying to change from a single to dual is not an easy task. You must know a lot about wiring as well as HVAC systems as well. This project requires not only swapping the HVAC climate control but also the entire hvac system with wiring to a dual climate ECU. Can it be done....Yes. Is it easy not even for an experienced person customizer. While doing a plug and play oem navigation for my 05 legacy I got asked about this. While my car had the dual climate control and my buddies did not the system was far more advanced on mine then his.