Tom claimed it blew 75,000 BTU at the top end during the EPA test. That test doesn't try to hit a sustained high-output burn. Tom is confident that it can burn at a much higher output than that, but refuses to play the numbers game that other manufacturers play. He said he feels that just showing the real-life EPA test results says it all, with no need for manufactured numbers. Same thing for the efficiency numbers. Claims of specific overall efficiency coming from the industry have always seemed suspect to me. Woodstock doesn't want to play that game, and I have lots of respect for them for taking that stance. We all know it will be more efficient than the 72% that the EPA arbitrarily assigns to cat stoves, beyond that you'll just have to buy one, burn good wood with your best technique and see for yourself. There were no doubters at the get together, only talk of selling the stove they have and getting a Progress. Heck, that stove is so nice I don't even care that they called it "Progress" anymore. You should have seen now fast we scooted away from the stove after they snapped a group photo in front of it. And that was when it was it slow burn mode. I've seen my Vigilant get a lot angrier, but it used up a lot of wood doing so. This nice big stove just pushed out the heat for hours on a couple decent splits of ash. Of course, it was Sav-ash, so that may have been a factor.