I am sure someone can help you that is more familiar and possibly in the business... but as far as I know, there are a few types of finishes for vinyl stripes... Matte, Gloss, etc.
I have gloss white and they are anything BUT dull. They look great, in my opinion... Because the orig. installer messed up a spot on the lower back bumper - We're having another guy fix it this spring... Just make sure whoever installed, you've seen their work and is trusted to make good if they mess up!
Dark, Smoke Silver with black outlined stripes would be cool.
Try this site:
Mustang Stripe Painter