I am working on sorting and writing up captions to some actual installation pictures from my install in my brother’s ’05 Impreza and other installs.
For now, here is an electronic “How-To” from an online vendor. It should help get you started:
Below, take a look at a photo set from Travis D., who did an install in his 2004 WRX. He elected to use 5.25″ speakers in the front and 4″ in the rear, though 6.5″ in front and 5.25″ in the rear were possible. In the end, the custom brackets were a good way to be certain that the speakers fit perfectly the first time. He also decided to do direct wiring as opposed to using the Metra wiring harnesses, but that is an individual decision. There isn’t a single right way to do the install, but there are many wrong ways. This is one in the “right” category:
Front door, stock:
Laid out to pre-drill the mounting holes:
Test fitting the adapter in the front door:
Front stock wiring, then with the connector removed, then with crimp connectors. (NOTE: another option would be solder and heat shrink or to use blade or spade connectors right on the ends of these wires)