Welcome to the forum

Well, the the HIGH is for the MK2-CD/MK3-CD/MK4-DVD and the PRO is for the newer I-drive systems, PRO discs have PRO written on them.

You say you have a 2003-1 CD so is your drive a MK3? if so, neither the HIGH or the PRO DVD will work, you will need the HIGH CD.

Hope this helps

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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.