Did a dirt road chasing a mate of mine. For about 5 miles I tried passing him in the dust but it was so thick I couldn't see anything as I got level with his back wheel, and twice got into a tank slapper as the track became too loose.
After 5 miles I gave up and sat back in less dusty conditions until I found some hard packed stuff to pass him.
Point is; it was great test for the UniFilter.
Bike is a '13 with original airbox. Here's some pics.
As you can see, the pre-filters in the snorkels are filthy, the prefilter in the airbox has a wee bit of colour, the inside of the main filter is clean and the airbox is spotless.