Are you sure these are exclusive to the convertibles? I swapped out a cat-back system for a friend with an L99 coupe about a year ago, and could swear it had the valves as well. I was concerned at the time what impact it may have on the AFM, since I figured that was its purpose. She's never had an issue since removing it.
My love is in league with the freeway. Its passion will ride, as the cities fly by, and the tail-lights dissolve in the coming of night. And the questions in thousands take flight ~Robert Plant - Big Log~