The G37 vent is mounted in the Impreza rear cover and the duct adapter is test fit. Originally the duct adapter was going to be glued in place, but leaving it a slip fit was a better plan for being able to assemble everything in the car.
In the car, the center console rear cover, the parking brake boot, the center panel around the shifter with the cup holders, and the left and right front sections are removed. The 4 mount bolts that attach the rear of the center console to a bracket at the floor of the car are also removed.
The passenger floor vent duct is removed and the cap off is installed. It attaches with one screw.
The driver side floor vent duct is removed and the cap off is installed. It's a snap clip installation on 3 sides.
The left and right connection ducts to the underseat vents are removed. Pulling up on the bottom/back part of the duct and then pulling the duct to the back makes each one come out pretty easy.
The remaining under dash connections will be the air supply for the rear vent. The adapters are now installed.
The rear of the center console gets lifted up a little so the air manifold can be slid under it. It then gets bolted to the floor bracket so it can't move around.
The cover with attached vent gets slid into place and installed. The rear is now done.
A layer of carpet padding gets laid on top of the driveshaft tunnel to insulate the AC hoses from tunnel heat. The intent is to keep the cold air cold. The harness connections for the USB and line input in the console will be between the 3rd and 4th hoses. I added a slit to the carpet insulation so the harnesses could pass through.
The 4 hoses are installed. I installed the back end first for each and then routed each to the connection points up front. Each was 33" long. The #4 hose on the right side could have stood to be 1/2" longer, but it worked out fine.
A pair of hoses go to each side. One on each side of the center console mount bracket and one each further down the side of the center console panels. The left side hose goes around the parking brake. There is no interference with the parking brake, the brake switch, or the shifter. The carpeting is under the hose in each location. Hoses are never routed under the carpeting.
When installing all of the canter console panels, the trickiest parts were getting the screws that connect the back and front side panels together and getting all of the connection tabs in place between the front panels and the dash connection points on the sides of the center cubby area. That took a few tries. The center piece around the shifter won't snap into place if the side panels aren't correctly connected. But after that, the job is done.
I'm very happy with the final results. The airflow is pretty good to the back, with good adjustability. I honestly don't think it would have been much more airflow if it had been Subaru original equipment. I actually could have left the driver and passenger floor vents installed, but I wanted to make sure I got as much air flow to the rear as possible. The hoses have a bit of ‘that new PVC hose smell', but I'm pretty sure that will go away over time.