2007 STI - 67K miles
Ok what would you check first? This isn't something I've really dealt with before but it seems to be getting worse very slowly..
Usually when turning left I get heavy vibration in the steering wheel, and some light power steering moaning. The wheels must have good traction to cause the issue. IE if there is snow in the corner, starting from a stop, it is smooth but as soon as I round the corner if I hit dry pavement the vibration comes in until I straighten it out. Low speed corners will cause it the worst. Bumpy or crappy road conditions even when going straight will cause it to a lesser degree than slow turns (like under 10mph).
Stock rims, snow tires wearing evenly (havent checked balance or alignment), Factory suspension and all parts included in the hubs, axles, etc. Feels like it has more to do with driver front wheel.