Speak to your dealership first, but be mindful of them quoting you a ridiculous price for updating your head unit. I was quoted +£200 to update mine, but I found a motor parts company that sold me the software download for £20!
As a side note: if your head unit also has built-in satnav, you can also get a map update from: www.satnavstore.com
. the mapping software for my car cost around the £35-40 mark.