I think with whatever you do on the hood, you should follow the lines of the groves that are already there.. If I were to do anything with a different color decal I would take the middle section of the hood and run it all the way back over the roof and rear spoiler, rather than doing just stripes. That way, it matches up exactly with the grill and you could bring it down the front bumper if you wanted to.

I had my carbon fiber hood painted in a similar fashion, though I don't have anything on the roof to continue it through the rest of the car