I am having some work done on my existing HVAC system have met with 2
contractors.

One contractor has pointed out that I have several ducts at the end of my
supply plenum and that is a NO-NO. He suggest that this should be corrected
by making the supply plenum larger and having all ducts come off of the
sides of the plenum. Another contractor is not concerned about this and
suggest that the use of manual dampers is sufficient.

How much of a NO-NO is it to put supply ducts at the end of the supply
plenum? We could use better air flow at the ends of the house and I was
wondering if the larger plenum with all ducts to the side would help.

Thanks for any advice you can provide.

George