Crazy about the trap. I still don't get how people don't know how to run a drain.
About the filters. Are people saying there's a problem there? If so:
We use a mini-pleat system. Our mini-pleats, have quite a decent PD. To compensate for the PD on anything over 3 ton, 2 mini-pleat racks are required. You can "double stack" like they did, if you don't have the room. It would be preferable to do a "wrap around", where you tag both sides of the furnaces, rack on each side.
"Better tell the sandman to stay away, because we're gonna be workin on this one all night."
"Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."