It depends which map you want (with what kind of features) and the Navcore to use. If you want a map with IQ routes and all the features I would suggest a 9 series navcore. Please see this and choose your map and Navcore:
if you want all the features then you need the 850.2800 map. You will find it here:
For the Navcore look here:
The best way is to backup your system, flash your memory and start with a clean istall. If you decide to use a standard Navcore you will have to patch your ttsystem as well as your map. In SE Navcores it's already patched.