Seer 23 has been mentioned by the last guy, he's very thorough been over here asking questions and narrowing down the details.
The OEM ducting is in my way and just plain silly.
The furnace is in the garage, it punches through the wall and gets converted to a round duct that goes down 6', reduces into a couple trunk lines then spider webs the individual vent feeds up 8'. He wants to put it near the ceiling for much improved flow and it will get me some floor space.