Some may cringe, but on the blue coupe I used non hardening seam sealer, 3M. I hope to never have them off again so if it does harden... whatever. There should be a small opening in the bottom though towards the front wheel to let any water out (double-edged sword). Also, if you were to take the rocker cover off there is a seam below the edge of the front of the door. That needs to be clean of debris as that is a major drain point for those front fenders- from what I can see. Others will know more than I.