Static preasure

[hotsummer101]

without getting too technical and using measering tools,
I have a 2.5 ton a/c + gas heat unit in a 1100 sq ft home that
cools OK and puts out a very decent (again without measuring)amount of air flow , house has 6 outlets, I am thinking of putting a 7 th supply outlet,if I do this technicaly I would assume that the air speed will go down a bit and the tempature coming out of the air grill to get colder as well. Am I correct ?

[beenthere]

Not really.

when you add that 7th supply, all the other supplies will lose some of their air volume, but the blower will also be able to move more air, and more air means a slightly warmer coil, which means the air won't be as cool as it was in cooling mode, or as warm in heating.

[morris-jenkins]

adding the 7th supply could actually help just remember that your furnace cant put out any more air than what it takes in meaning you cant get 1000 cfms out of your furnace if it only has 800 cfms coming into it from the returns.

[dash]

After you add that suppply,check and adjust the charge,as it's likely wrong.