I don't think Cali models have some sort of modification in the cat-converter or the exhaust system to make it extra envio-friendly. my impression is that EU standards (which the X meets) is stricter and higher than any of the US vehicle standards so the X didn't need any of that.

Someone correct me if I'm wrong

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2007 4.8i Space Grey, 20", black nevada interior
All options with no 3rd row, rear entertainment,
handling pkg.