My door panels flex more than I'd like them to, plus they just don't feel all that strong. Not sure how I want to go bout strengthening it. Was thinking I could just put a ton of spray foam that hardens up on the inside of it for strength, plus it would be a good barrier for sound too (lot of sound come my mids/highs leaks out my front doors). Other option I was considering was to put some fiberglass resin on it, most likely combining it with fiberglass mat.