Hi you need special keys to remove the unit it is two flat pins which are inserted at the bottom of the radio, you will also need a facia adaptor if replacing the original unit. the only way you can attach a cd changer to the original unit is if it has cd changer compatabillity, if so you may be able to get one from the dealer or i belive sony do a 6-disc changer which is designed to fit your original system at around £200. matt