their idea of sealing the foundation vents was to ... greatstuff foam the metal dampers?
should be mastic sealed 2" foam behind the door.
the 10 mil vapor barrier is also great stuff foamed? also a fail. all the plastic is supposed to be mastic sealed to the brick.
also, 10 mil is about 1/2 what I'd use. then again, you got a low price, it may work for your needs.
The TRUE highest cost system is the system not installed properly...
The three big summer hearththrobs...
The A/C repairman