Before the new air dryer and new plumbing the front air bags would leak down overnight and no air in either tank. Now after the repairs it took 3 1/2 days before the front airbags dropped @2". But both tanks still held @105lbs of air, down from 120. The truck shop did say there were 2 minor air leaks left but really nothing to get excited about. Not sure you can get any system 100% air tight, at least from my truck driving friends, they tell me I should be good to go.
Now cleaning the roof and doing a little caulking, still have the ball joints to clean and wrap then buff out the coach and wax....maybe someday I can go camping.