I think it all depends on the color, i would have to see the silver side by side with black though to decide what i myself would choose for a red car, but it should look sweet so long as it flows, unlike the yellow or orange.
They offer a bunch of dressy stripes and such for the Focus. I like the Saleen style. But my feeling is that stripes makes the car appear a bit too busy. The car is clean, almost too clean with no emblems or markings on the sides. The ST model only has one tiny st emblem on the back. But, it may make the appearance too busy.
I personally wouldn't do it, but I'm into a cleaner, simper look myself. In the end, its up to you to decide if it something you like to look at. I do stuff to my car people don't like at all, but it makes me happy, thats all I care about.