I think you are correct that the seems to be a dye preference. I found Taiyo Yuden -R premium line works on the MK 4, when TDK and Memorex -R's would not work. Interestingly cheapo CompUSA 4x -R's also worked, but CompUSA doesn't carry the 4x anymore (I believe they were manufactured by Princo).

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David

Macan Turbo / 997.1TT (gone) / e83 (gone)/ e46 M3 / e90 335xi (gone)/ Sienna XLE Ltd
B7 A4 2.0T CVT (gone) / Pilot EXL-RES (gone)