Joe Hutter indicates in MMD 06.07.20 that the Ampico pedal pneumatic
operates sluggish due to the inlet tubes being 3/8-inch in diameter.
The piano is a grand player from his description.  He wants to fix it
by increasing the nipple and hose sizes going to the sustain pneumatic.

This may be true, Joe, but I would not change anything.  If you did
try to increase the diameter of the tubing, you will run into another
problem in that the tubing won't fit between the tiers and will cause
nothing but pain in others areas.  The rolls have been coded in such
a way to expect some delay in the operation of the sustain pneumatic,
but you can minimize and control these issues in a different way.  The
biggest change being to reduce the travel of the sustain pneumatic.

You want the sustain pneumatic to move as little as possible and still
have all of the notes sustain correctly.  This adjustment is directly
related to how well the damper rail is regulated in the piano.  It might
even be that someone has used spongy felt between the linkage points
which adds to the problem.  To do it right, replace any felt with
leather or use thin felt only.

The fun part begins when you remove the keyboard action from the
piano.  Use the sustain pedal and watch when the sustain rail starts to
move up and when the sustain dampers start moving off of the strings.
If regulated right, the rail should move up very little before all of
the dampers start moving off of the strings at the same time.  If this
doesn't happen then you have found the problem and the dampers need to
be regulated to the damper rail.  Some times this can be done by simply
turning of a regulation screw or can be as complicated as adjusting how
far the wires are pushed into the damper block.

After the dampers are will regulated, then the adjustments between the
sustain pneumatic and the damper rail can be addressed.  Adjust the
push rod so that there is almost no lost motion between the sustain
rail in the piano and the pedal pneumatic when it is inoperable.  This
includes the rod coming up from the foot pedal.  Now adjust the screw
on the pneumatic so that when it closes, the dampers just rise up off
of the strings.  1/8th inch is good, the closer the better, but
remember that there may be problems with humidity changes if you get
this adjustment to small.  The sustain pneumatic should not move very
much to get this to happen which quickens its operation.  If you find
that the sustain is to quick, just increase the lost motion or the
travel.

Another reason why the damper rail may seem sluggish is that there is
a problem in the bushings found on the damper lever that contacts the
back of the key.  I have worked on pianos and found that both brass
pins on the flanges being caked with green goo that caused all of the
dampers to drop slowly and cause the timing issue.  To detect if this
is the problem, remove the piano action and test each sustain lever
where the key hits the bottom of the sustain lever.  Find the one that
seems to return the slowest and remove the sustain wire and try it
again.  If it is still slow, remove the single damper lever and the two
flanges and check for stiff movement at the flanges.  If you find they
are stiff, you may have to re-pin or re-bush all of the flanges.

Good luck, I hope this helps.
Pete Knobloch