I am coming from a modern non-cat to the BK and I did not get the big smoke show with the non-cat during reloads and startup. Nor do I get the smoke show with a campfire in a pit. I propose that the huge excess of air being fed to the firebox in a non-cat feeds the fire more air for a cleaner burn but also dilutes the smoke into a lower concentration, higher temperature output. During the burn, the non-cats are dumping huge amounts of air into the fire and above the fire which continues to dilute the smoke and more importantly the inefficiency of the non-cat technology lead to much much (like double) higher flue temps so the smoke goes up and away to be better mixed with atmospheric air. Compare this to a cat stove with cold flue temps, small flow rate in the flue leads to a very high concentration and cold smoke that lingers near the chimney cap and is much more likely to sink to ground level for smell. Emissions are measured in grams per hour right? Well, slow down and cool down the smoke from a non-cat and it may look like what we are seeing from a cat. Same grams per hour but diluted. In school, they taught us that "dilution is the solution to the pollution". Well yes, the local effects are reduced with dilution but the actual pollutant load is unchanged. That's my current theory. 24 hour burns for nellraq means he is doing something right.