Hey.
Just did this upgrade.
Same response as Fish, I used a little Gorilla tape to ensure the "U" shaped plate adapters were tight.
I can't tell any difference in terms of air flow from before and after so must have done something right.
I added a Kenwood DNX unit, transforms the look of the car.
Also added a rear view camera hooked into the unit.
Fitting the camera and hooking up the cables for Blue&Me was a pain though, you need to remove seats and panels which was easy but time consuming.
Cheers.