I have stage 2 dna on my r along with k+n stage 1, kev fuel mod, snorkel removed and air box drilled. The difference is considerable with more power right through the rev range. Theres so much more torque meaning theres less need to down change when plodding along and 2 up but if you want to give it rice then the powers there for wheelies and tyre chewing antics right through to the limiter.
Theres no issue with dirt getting in and unlike paper filters the dna can be cleaned and re-oiled. As maxwell says just dont hit it directly with a pressure washer etc.
And as he has said the fuel consumption depends on how you use the new found horses. My consumption has gone up slightly as I cant leave the horses alone but if you have the discipline youre ok.

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I'm always in the sh1t, only the depth varies