Yes, I actually took out a little silver ball bearing and made my fuel mixture richer. I read that if fuel mixture is too lean it may cause the engine combustion temp to be too hot which can increase NOX, so I turned it clockwise to make it a bit richer. I do not have a duty cycle or a way to check %'s so I started the engine and slowly began turning it. The idle didn't seem to change much after I restarted engine, maybe slightly lower by a fraction of what it previously was and there is no erratic idling. I did notice that after doing the mixture adjustment I got 325 miles on 1 tank of gas, combo city and highway driving, but I normally average about 280-300. I haven't gotten any cel codes either. Maybe the engine was running leaning because I did notice that after smog my nox was higher than all other components and the cat was installed the same day as smog and engine was warmed up. here is link I used for fuel mixture
BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT