[Hethj7]

When you are painting parts like that you need to use a flex agent additive. Those plastic parts like on the bumper of the Mustang or on bikes will flex and cause the paint to crack.

I am not sure if the paint will work correctly with your original spray job, but I know when painting parts like this the flex agent is needed to get good results. It may not be the complete fix to your problem, but it should help.