Well, even if they aren't OEM just as you said the Knockoff GT2 wing alone costs 3.5K so I would think the price is pretty good at 4K.
I agree with the others as far as the badge goes. I think its all good if you don't put a GT2 or GT2RS badge on the car. The GT2 is such a good looking car, and that wing looks so much meaner than the Turbo. I would say go for it. Leave the Turbo badge on or just de-badge it. Who cares what the small % of people think. I have a 996 GT2 and I still have been asked if my car just has a body kit and badge... So it can go either way. I say do it. I wish my car looked liked the new GT2 : ) They look BadA$$