[franken]

Well, my opinion is the up down air line design is no bueno and prefer a horizontal top in back and forth design. This means air has to be in the air tank, get trapped at the end by a dryer or go out in the air. That's exactly 2 places to purge water. Each horizontal run in my garage is 20' so I also have room to grow the system.
You need to blow off a little air from the bottom after running the compressor to get rid of condensation in the tank. This is universal.
An up down system means you need to blast those valves out everytime the compressor is used and you're done using it for the day and the air has cooled (or tomorow). I promise some black water will shoot out if you ever forget. Nasty.
Poor design.
For a 2 car garage you don't need a bunch of drops so it makes sense to do as I have and have a manifold at the end with multiple outlets. It's the same argument as above. If you have a horizontal overhead system with vertical drops, you have to purge each drop of water after the air has cooled each time the compressor runs.