There is a way to get rid of all the sags and wrinkles on the Kyosho Mustang. Just let it sit out in the sun for a couple of hours, then bring it in and use a heat gun on the covering. Keep moving the heat gun over the sags and wrinkles, and the covering will tighten up. I used the heat gun on my Kyosho Spitfire and ME-109, and the sags and wrinkles have yet to return.