If you haven't purchased your S&B particle separator I highly suggest you DO NOT use the under fender mount.
The are numerous problems with that unit. Myself, my neighbor and others here have issues that it just does not work as they advertise. It allows too much dust into your air box. I have been working with S&B on this since November. All fixes have been installed as well as a totally new unit installed by S&B at my house. Nothing they have done has fixed the excessive dust problem.
This photo is with driving about 200 miles in the Arizona desert. My neighbor has all the issues I have.
If you must use S&B I recommand their rollbar particle separator. The under fender unit just can not handle the anount of dust because the intake is located on the side of the bed in the rear. Personally I think it's a design issue but S&B will not admit that.
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