According to Renntech, the code is 3AU (water based paint). It's 3AT for the conventional paint. When I got my side skirts painted this yr, I had the paint shop use the water based paint code for Arctic Silver, and it came out matched perfectly. Oh, I gave them one of my painted bumperettes to help them match too.
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2006 Audi A4 Avant 2.0t Quattro
1997 Boxster Glacier White w/facelift(gone but not forgotten)
2004 Boxster S 550 Spyder Anniversary Edition