I have been thinking about building a sub, I built one for the living room. My wife is having a rummage sale this weekend so the garage is full of stuff to sell, I am kinda annoyed, will be happy when its over. If I shut everything up tight I can play fairly loud without encroaching into the neighbors windows, but when the garage door and windows are open I need to be careful. But you are right a sub is in the future.
Oh yea, you asked how they sounded? I have them sitting on adjustables shelves in the top corners, They are out of the way and wont get damaged, they sound good. As you probably well know garages dont have very good acoustics but all things considered they sound great. Lacking a little bass but like we mentioned a sub will take care of that.
edit,
Here is how I have them , I know it is not ideal for "critical" listening, but they are out of the way and actually sound good.