From that diagram it looks like it is just a little deflector though, right? Similar to what Porsche puts on the Caymans and 997's? I don't think that can even be compared to a hole for a hose and backing plate setup. I put the 997 GT3 deflectors on my Cayman just because it was a cheap upgrade, but I never really expected it to be very efficient.
I am just speculating, maybe the deflectors do something decent, but I wouldn't really be that much more pleased unless they included a convenient hole for a hose and backing plate.