http://www.paintscratch.com/
I used these guys for touch up paint on my black 94 rt/10 it matched perfectly.
Viper Black Clearcoat X3/MX3.
"If you are painting a flexible surface (such as a rubberized bumper) and you are spraying the paint, you should order the Bulldog Adhesion Promoter as this is required for proper adherence for the primer, basecoat and clearcoat. The adhesion promoter is only required when you are spraying the paint and not for the touch up bottles and paint pens."
This is a good site that should be able to answer all your questions.