I did my own. First I straightened it out and prepared the surface. Then I painted the black background using a semi gloss spray paint. Finally, I hired a local sign painter to hand paint the letters and numbers. I took the good plate down and had a paint shop match the color of the yellow for me.
They were still a bit shiny for my tastes, so I top coated them with an eggshell sheen clear.
Yes, they used to be blue and yellow, but only a few notice the inverted #'s & letters. Been on the car for 5+ years with no problems yet.
