Just wanted to share my choice for mounting the Cobb AP in my 11' WRX. After doing a little research I decided not to purchase the Proto Mount for the following reasons:
1. too many reviews on the vent clip sliding around; and
2. $30 for a piece of plastic! wow..
I chose to go with the Arkon SM050-2 slim-grip smartphone holder with GN047-SPH (vent mounting clips) - $11.99 with a free shipping coupon I found online.
GN047+SPH+SM050-2: Vent Mount with Universal Cradle for SmartPhone - Mount for HTC ThunderBolt
Review: The SM050-2 comes with 2 sets of rubberized arms that can accommodate devices from 3.5" up to ~8". The small arms work perfectly for the Cobb AP V2, whereas the larger arms are easily interchangeable if you wanted to mount a cell phone or GPS. The cradle uses ball pivot similar to the Proto Mount that allows 360 degree swivel of the device.
The GN047-SPH vent mount was pretty much useless. I would compare it to the reviews I read on the Proto Mount as it slides around and does not hold firm to any vents on the WRX. I decided to cut of the brackets for the vent clips, and add 3M double sided tape to the swivel base.. it mounted perfectly to the surround above the dash light control.
Here are some pics for anyone interested: