West Wings I believe, and the quick google search for WRC spoiler I did turned up a whole body kit to go with it. You may be able to find just the spoiler somewhere on the net as your not the first person to ask about this one.
Moved to "MK1 Focus". There are some companies out there that might have one sitting in the back stock room that no one has ordered. You just have to keep searching now that you know what keywords to use.