Thanks so much clearing up the situation of CO and O2.
Desert Racer you are correct, my South African bike is so much more potent than the one in Aus and I'm just planning how to fix the "problem" in Aus. I'm taking a DNA air filter with me for that bike and will probably ride over to Kev to get an O2 controller from him.
I was just under the impression that when the DNA filter was installed (with aftermarket pipes), the standard A/F mix gets too lean and that's why the technicians here increase the CO to richen the fuel mix a bit.

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.