Check the threads as suggested before you start replacing things. According to 2009 owners manual, the language is set by the nav/radio unit. Also if you replace the head unit with anything other than stock, you will lose some functionality. It is an opinion what you might lose. I cannot comment as I have never run my cars without one. Lastly if you buy used, it will need to be programmed with a Tech2 since the VIN is recorded in the unit upon first install. All the used units have the existing vin from the donor vehicle. The only way around this is to buy new old stock never installed. It will then boot normally.