the gt3 bit looks the best - designed to block the downward flow (and match the bottom profile of our bumper covers) and vent towards the brakes. combined with the 997 duct piece from the renntrack post should work well. the gt3 liner is two piece, however, so either trim your current one and hope there are suitable attachement points, or get the rear portion of the gt3 wheel well liner as well ...
http://www.autoteile-ab-lager.de/bilder/produkte/gross/Porsche-911-996-99650422391-8162.jpg