I'm working with the no till guys. That is where my Fatboy is going to go if I can ever stop tweaking it. I have been testing changes to the flue design by adding a long slot which creates flue vortex effects for improving the gas burn up and reducing the air flue mix.

For those who are interested I had access to a $15k Tesco flue analyser for a weekend. I did some tests on what looks like my clean burning flue design. I have since changed the flue design and it still needs more tweaking.

After discussing the results below with James Joyce (BiGchar) he suggested I try the below set up (now implemented... sort of )

http://www.youtube.com/watch?v=1bJXop5kkpA

The vortex results from the air coming in via the split in the side. Very nice for generating mixing and stabilising the flame. Vortexes are used extensively in industry for flame stabilisation and to make flames tolerant of incorrect air fuel ratios. Not a bad idea for one of your units Baz.
This is the results from my 75 litre Fatboy Gasifier using dry wood chip and leaf matter from road side chipping. (old flue design)

Just after start up from the top of the flue

696 NOx mgm2
1.23 CO2%
172.4c FT
0 H2 ppm
32 NO ppm
19.22 O2%
1244 CO pmm

15 min after startup from the top of the flue

696 NOx mgm2
2.46 CO2%
305.5c FT
61 H2 ppm
60 NO ppm
17.61 O2%
519 CO pmm

19 min after startup in the condenser/hat. (this is the connection area between the main unit and the flue, this has a small gap to allow extra air in. This gives you a bit of an idea on how much gas cleaning goes on in the flue. The gases should be in the flue for at least 2 seconds while mine is less than 1 second. My next system will have a much better flue design based on a basic cyclonic thermal oxidiser.

904 NOx mgm2
4.99 CO2%
321c FT
0 H2 ppm
166 NO ppm
13.89 O2%
3702 CO pmm