Just finished an install on my '01 Audi A4. I had to build a custom fascia plate for the dash, made out of MDF then covered it in black vinyl.

Wiring was too easy. Just swapped the pins on the Rio Car cage for switched ignition and memory, and it stuck right into the factory harness for the Symphony radio. No third party harnesses (or even the extra harness Rio sends you) needed.

Sound is exquisite.

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Rio Car (10MB) Blue Face (looking for Red)
'01 Audi A4 2.8 Quattro