What is the law with removing the cat? I know a lot of people are leaving it off and I was wondering if its worth the possible trouble it may cause with emission testing. Or do diesels require the same emission tests as gassers in Colorado?

 

Yes there is a diesel emission test done on the rollers, and yes, if they notice any emissions equipment ain't there like a catalytic or excessive smoke they'll flunk you.
The test is different than the one they do on gassers and only done at approved diesel inspection stations.

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