Yes I have used it.
I do not have one on my current YZ. The plastic cage seals the Twin Air filter just fine.
I did not like the fit of the DT1 filter with a stock cage. The stock filters tear too easy.
i had one on a 06 crf450,it was the complete kit with the aluminum filter cage and base, sealed great and filter changes was easier due to the threaded stem on the base being shorter