hi, im new to this site and i have just bought a 2004 m3. i love the car and everything about it however i cant get use to the factory sat nav unit as it feels very dated and not greatly simple to use so i purchased a new sat nav unit from ebay which pretty much looks like the factory unit but has all updated things included such as bluetooth and mp3 facilty and dvd player etc. Now the problem is i took it to my local auto electrician and what they thought was a simple job proved not to be, they have told me its going to cost alot to fit my new unit due to all the extra wire it will need as apparently the factory unit in the m3 is just a slave unit and the main unit is in the boot? is it really that big of a job? is there a wiring kit i can buy instead?