I have the BC box and it's a cool idea, but it could be improved on. It's a bit too small for filters. A DIY solution could address this. If you not cramped for room on the fender you could use a bit more fender and move the filter to sit at a 45° in the box and it would be a much better fit and the intake hose would be easier to make. The box could also be a bit taller to facilitate more filter options. After some searching I did eventually find an AEM dry filter to fit the existing box.
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