Okay, I got my new 80 insert installed this past Friday and boys and girls I'm here to tell you it is a beast! I can't even imagine what the 80's big brother, the 91 will do! The first thing I noticed was it just seemed to be getting too much air. Burn times were shorter than I expected and it was easy to reach max safe cat temps with very little wood. Long story short; I read about sloppy air controls on the 91 here and sure enough there was a lot of room for air to get into the stove with the shutters fully closed. To correct the problem I took the point of a screw driver and bent the sheet metal rails, on which the air control shutters slide, up a tiny bit. This forced the shutters tight against the stove body and the whole dynamics of burning changed for the better. Cat temps down, burn times way up and I can load the stove full without worrying about frying the cat. There is more resistance when opening and closing the shutters but that's good as the shutters are now very tight against the stove body and no air can pass through. Just thought I'd share, hope this helps Edit: May apply to other Buck models and other makes as well.