I'm in St. Louis but in and out of Springfield every once in a while.
I got my STI from Stephen Bolen at Reliable, Had a good buying experience , if there is actually such a thing.
You're going to need to get snow tires ASAP as the stock summer tires don't like winter driving conditions, and the supply of good snow tires be gone quickly. You might actually need to buy them now even before the car arrives.
Also the people at Car-Fi (Andre) on S Glenstone took excellent care of me and actually have installed car stereos into STI's, mine and at least 1 other.
Installation apparently isn't as straighforward as it should be and it need a different than stock stereo adaptor harness than what the manual says.
I have a picture of the stereo going in if you want.
Thanks for the information on the tires and car-fi. Just curious, what type of winter tires did you buy? At the moment I'm looking at Pirelli PZero Nero M&S or Michelin Pilot Sport A/S. Any thoughts? By the way, I would love to see some pictures of your car stereo.