I am not an expert on organs (truth be known, I know very little about
them), but I am an engineer.  The discussion thread on pipe lengths has
generated some interesting responses, some saying longer distances are
no problem, others recommending keeping the distances short.

From a purely engineering perspective, what we want to do is to deliver
the required quantity of air at the required air pressure.  The longer
the pipe length, the bigger the pipe needs to be.  As long as you can
deliver the maximum amount of air the organ requires, at the required
pressure, you should have a workable arrangement.

Ray Fairfield

 [ It hasn't been clear in the discussions whether the pressure
 [ regulator is located at the blower or by the pipe chests.  If it's
 [ at the blower then the dynamic pressure drop caused by the pipe
 [ impedance is a major consideration.  Gebroeders Decap Herentals
 [ evidently install the regulators at the pipe chests if possible,
 [ to avoid the impedance problem.  Compounding the problem analysis
 [ and solution are the resonances of the pipe: it's really a
 [ transmission line with AC and DC air flow.  -- Robbie