i wouldnt hose it out because you will get water in the car, but you could take some cleaner and clean it and then wipe it down with a damp rag. i assume you are talking about the part that is covered by the rear molding when the top is up.
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1994 Mustang GT, just a few minor appearance mods, engine mostly stock (for now)
Mine has some dirt building up along the top in the insulated part of the windshield where windshield and top come together. I was just going to try to clean it out with a slightly damp rag but compressed air sounds like a much better idea, thanks!
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washing under top - 
