+1 on Khan, I've always gone to him or his now deceased Dad for all my non-DYI BMW stuff and when I am too lazy to change tires myself. He is always great.
As for the the Triumph dealer in Manassas Park, they also own Advantage Certified Auto next door and if they run the mo shop like they do the auto dealer/shop then they should make most customers very happy. I bought my 330i from them in 2008 and gone back for service and a friend has gone to them after back experience with dealer and J&F Motors and was very happy with Advantage. Ken Davis the owner/Pres is a mo rider and really into bikes.
ADV'ing from America's fine Crapital...