-1 For the Cobb. Fitment was almost non-existant on my 05. Two of the three bolts lined up and the 3rd either needs a metal braket to extend it or as in my case a zip tie to secure it from flopping around.
Gruppe-S doesn't fit our cars. It's WRX specific. I commented on it in their Vendor thread. I got one with my Helix DP.
I made my own out of some ducting from ACE using rivets, a drill, and bending it with my vice. It doesn't look to bad, but then again, nobodies looking under my hood. Their best view of my car is usually from behind.