Never had an issue with. Title/registration still says 4dr. If ever pulled over I guess keep a picture or two of project in glove box to show em was a 4dr... If they ask.

I guess a guy could have inspected also to have title show 2dr but not sure how that would play out if sold down road. Ethically one would want to pass on to others down the road it was converted. Me personally, I leave title as is.