I have put together an installation guide from an install I did on a 2006 WRX. This is going to be similar for most Impreza and WRX cars that use the H7 bulb type. There will of course be some differences. All in all it is one of the easiest cars to install HIDs into the low beams. There really wasn't anything that caused any issues. The output was also amazing and the cutoff was just as you would expect from the OEM HID projector setup.
So how is the cut off line using the halogen projectors?.....and is there a lot of glare do to them being HID'S now?
The cut-off shown from the installation I did was almost exactly OEM with halogens. The customer said he noticed close to zero difference. With the HIDs this makes it perfect as the glare is almost non-existent.
I just threw in the bulbs on my 2008 rex , and had no glare problems on the low beams...........mounting on the 2008 rex was relatively easy , as we all know , there is minimal space . I also installed hid's in the high beams, I just stacked my slim ballasts on top of each other and drill and screw them down.....high beams are rediculiously bright as soon as they warm up to 4500k, I love it !