Was wondering what the general consensus on this was, with input by both techs and installers. I was talking to someone I know who happens to do installs, and he didn't seem to realize the importance in adjusting anything from factory settings. An 80k/3 ton furnace with a 2 ton condenser would then be getting 600 cfm/ton (or whatever the ductwork would handle). He thinks of it as just airflow over the coil, and wouldn't bother adjusting anything. Is this usually the case you find? With variable speed blowers this would be especially important. That's why there are dipswitches. Makes me think twice about recommending a larger air handler for improved efficiency if its just going to be left at its 5 ton airflow setting, or whatever it may be, with a 3 ton condenser.