Hey gang, I've been experimenting like crazy with my stove these last few weeks, and am on to something sorta cool. I made a post about it over at Donkey's board, and thought I'd open up the discussion here as well in case any of you are interested in this minutiae.
It's a secondary air tube placed directly in front of the port. It runs vertically the full height of the port, and about 1"-2" back from the port entrance. There is a slot running up the side of the tube facing the port. I've designed and built a few different arrangements, with different results, and am not set on one configuration yet. Generally though, it's a secondary air delivery configuration with a CSA of about 9% of system CSA, positioned to inject the air directly in front of the port, while adding beneficial turbulence patterns.
Look at the clean burn time here, it's a very different rate than normal...