Yes, there's graffiti in Irvine, it's just a little harder to find than in some other places. But the directions that I found on the web were accurate, and led me to a storm sewer under UCI that's filled with art. Photo gallery here.

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Also, if you have any interest in street art, you need to see Exit Through the Gift Shop. It's still playing at the local art house movie theater here, a short walk from of all this graffiti. Whether it's all true, an elaborate send-up, or both, it's very entertaining.