Hi Spencer!  Just off the top of my head...  With regard to the effect
on airflow by the leg configuration between two tracker bars connected
in parallel to a stack through a Y, I am assuming that conditions would
be such that one of the trackers would be taped/cut off while the other
was being used to read a roll.

My _guess_ is that under these conditions the arrangement of the legs
of the Y would make very little difference since we are dealing with
laminar flow and virtually no turbulence at the intersection of the
tubes.  There may be some impulse delay but I doubt that the difference
would be measurable without some pretty fancy equipment and it would be
very unlikely to turn up as a performance problem.

Jim Heyworth
Sechelt, B.C., Canada