Since our house was constructed in '93. We've added large shade trees on west side, tinted all windows and added screening and WILL add more insulation to attic (perhaps bring up to R-49)

Presently, we have a builder-grade 3T Armstrong 10 SEER. With improvements made/will be made-could we go down to a 2 1/2 T unit and still keep the house as nice as our present 3T does? The only time the Armstrong has struggled to cool was during the month of hell in August of 2000.

One caveat that may interfere with this best laid plan is that we're seriously looking at an Amana 18 SEER ASZ18 and AEPF Air Handler for upgrade next spring. Thoughts or suggestions would be appreciated over these next 9-10 months as we move forward in the costly but needed endeavor
thanx yet again.