Well it's been -10 here in Vt for the past two days so I figured I'd try my hand at installing my new headunit I got for xmas. I was lucky enough to have a buddy who recently sold his STi and he still happened to have his 20 pin wiring harness and the frame to fill in the gap (mostly it isn't perfect but I can deal until spring). I ordered the forward wiring harness from ae64 with the steering wheel controls so I figured I'd practice my hand at soldering and connecting everything with this wiring harness before I get the "correct" one.
On a scale of 1-10 on difficulty I'd give it a 4. I've never soldered or done much in the way of wiring but I found that this was pretty easy and I kinda enjoyed it! I used shrink tubing to cover everything because I read using electrical tape isn't prefered. I know there is way to bypass the ebrake but I haven't attempted that yet because it's not something I plan on needing for a while. Taking off the old radio was extremely easy and didn't give me any problems. I did run into a problem getting the old bracket off the old headunit. I had one bolt that was already kinda stripped and just wouldn't budge but luckily I have some easy outs and I managed to remove it.
Routing the microphone was the biggest pain just because it was so cold and I had to have my door open to try and get the wire through. Now just figuring out how to use everything on it is the next task! Here are a few pics of my work. Oh this was done on a 2010 wrx.