If CO does a tailpipe sniff test, it may fail. Most states don't do that for diesels, but I don't know about CO. If they just do the visual, smoke, and OBD test, it should pass okay.

I agree about it being a waste of time to delete it. Other than sound, mine ran the same with and without it. With it the exhaust smell was a little less acrid, but even that was only after a long hot run.