Here are the close ones that I know of:

TurboXS
8041 Queenair Dr. Unit 2
Gaithersburg, MD 20879

Altered Atmosphere
8011 Cessna Ave.
Gaithersburg, MD 20879

Curry's Auto Service (2 locations)
Chantilly
Curry's Auto of Chantilly is located in the Sully Industrial Park in Chantilly, Virginia. We are just south of Route 50, and just east of Route 28 near the Capitol Expo Center
Dulles
Curry's Auto of Dulles is a mile and a half west of Route 28, on Moran Road in Sterling Virginia. We are located just seconds from Exit 8 (Route 606), of the Dulles Greenway.

That's all I can think of off the top of my head. I'm sure the DSM and Subaru guys will let you know if I forgot any.