I'm determined to keep leaves OUT of the cowl, so I lined the fresh-air openings with 1/2 x 3/4" closed-cell foam weatherstrip, and zip-tied the sprayer tube to the valance.
Note that all the tabs along the back (bottom in the pic) edge are pulled DOWN so that they'll lift the valance high in front of the w/s. Later, the trim will pull it back down, and the force between them will prevent rattling. This is especially important at the outboard rear corners, where there are no screws. I added self-adhesive foam weatherstripping there.
Later, I added a dust/pollen filter here.
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