and how do I interpret the data?

I also sent you email on diagnosing knock sensors<ul><li><a href="http://www.ross-tech.com/vag-com/m_blocks/020-029.html">http://www.ross-tech.com/vag-com/m_blocks/020-029.html</a</li></ul>

seeing up to 9 degrees at around 5000rpms.. here is a plot..

<img src="http://images2.fotki.com/v23/photos/3/30429/200574/IgnitionTimingHighway-or.jpg">

You may want to find somebody with a TT Bentley disc/book to tell you what it should be for the 225. I've seen that spec increase to 12 deg. for the 170 hp engines, but who knows on the 225. It looks like you're fine.

What block were you logging to get the ignition timing curve?