I spray the stripe using a little touch up spray gun putting as little paint thickness on as possible so no paint line is noticeable after clearing the whole car again. I cringe when I watch those tv shows where they lay down a beautiful finish and buff the clear to a mirror finish then come on top of it and hand paint a pin stripe. When building a "50's" period correct car I can see to do that. With my 48 International truck I drive now I painted it semi-gloss black and had a pinstriper lay down some stripes and artwork on top of the paint. But when it is just a stripe down the side of the car I want all my stripes under the clear so it will never be damaged.