Hey Bill,
Resriction of duct work anywhere is never ok! Static pressure drop is
the enemy of air flow and would only increase with any kind of
restriction. The duct work should simply be re-arrainged to dump more
air where you need it and less air where you dont.
Because or static pressure you can only put so much air so far thru a
certain size pipe, thats the physics of air flow. I guarentee your duct
system is not "oversized" , so, any increase in static pressure will
back up all the way to the coil and actually to the blower squirell cage
and decrease flow over the coil, which at 400 cfm per ton of refrigerant
will decrease the total efficiency of your hvac equipment.