I'm new to the forums New Mexico . I have been looking at the z800 trial today I ask about the poor design airclener. I was informed that any cfmoto in there building has been upgraded with the inproved ari filter requested from the manufacturer.
I wonder if by improved air filter he means the CF Moto blue coloured foam filter. My 800 Trail came with one of those but even with me being diligent to try and stay out of the dust, still some got past as seen by my finger wipe and the dirt on the throttle body butterfly.
Here it is after 3 days of Idaho summer trails

Here it is cleaned.

But here's the dirt it let by.

I'm not unconvinced that a lot of the problem is that the air intake point is in the motor and back tire compartment so no matter how you avoid someone elses dust you still inhale what your own back tires are stirring up.
Still I think the aftermarket UNI is a better cleaner than stock. Unless CFM has come up with a better element yet.