Does the retrofit include the DSP amp? if the DSP amp is a retrofit then the car need coded so that it's an option (SAXXX) in the cars GM module, GT1 will add it for you.

__________________
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.