Just finished hardwiring my Beltronics STi into my 2008 WRX. I used the Beltronics DirectWire kit, mainly for the mute button and overall professionalism of the kit as opposed to similar eBay kits.
First off a picture of my car, detailed with M205 and my Porter Cable:
and the hardwire:
I had to make an extension cable for the power connection so i could run it down the A pillar and down the dash. Very pleased with the kit!