I think that you can if you have navcoder, its not something I've come across before, I've upgraded, downgraded and never had a problem, try a quick search as this has been brought up before.

P.S sorry your having problems.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.