If you have the 04 STi, the HVAC controls are plug and play, if not, there is a ton of wiring and extra parts you need to get, if you wanna upgrade just do the TR controls and bezels. Takes about 45mins to do the swap, you have to trim one bracket, and the ebrake cable. then you have to swap the 04 bracket to 05 bracket, that part cost me 20 bucks from SGP i think ???
This is the thread I followed when I did it