I had some rust problems as well. Tried to get real cheapo and did the rust removal thing. It's not worth the trouble. Get new rotors. I just did and hope to install this weekend. The Porsche mechanic gave me a tsk tsk look!
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2012 Panamera 4
2010 Boxster
2000 Boxster S 3.2L
1990 Land Rover Defender 6x6