S281 covers that. I didn't not remove my OEM light bar, because it'll then leave gaping hole there, and wing, although it covers it compleatly, will not make perfect seal(there is opening on both side by trunk lid nad rear fenders. vent i guess). And yes S281 wing does comes with 3rd brake light.
see the attached pics. you see Vent thing I'm talking about.
and second pic, you should be able to see the Saleen 3rd brake lights