Look around on this site and you’ll find that people highly recommend the stock air setup.
Yes, it can be expensive, and you’re almost guaranteed to have to adapt something, but it’s worth it for the bike to run as it was intended.
In your search for the correct air boxes you just may run into other parts you eventually are going to need as well.
Also, you’ll most definitely see how other people have tackled the problem.
Good luck with your search
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