Quote Originally Posted by doyleeoin View Post
Have you noticed any difference? I've just bought two pre cat ones for my M3 as it's on 106k miles
I haven't driven it much tbh. But the DTC is now staying gone. I'm going to change the pre cat ones in a week or so. Just to keep it tip top.
I'd be more interested in turning off the Auxiliary air pump than any of the lambda features tbh.

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