I have a '97 A4 2.8 Quattro.

I understand that I have the Delta CC head unit. My first question is: What are the differences between the Bose and non-Bose system?

My second question is: How would I be able to tell which stereo I have (besides the "BOSE" lighting up on the display -- I suspect the head unit may have been replaced by the previous owner)?

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1997 A4 2.8 Quattro
5 speed
100% stock