The technology disclosed herein generally relates to fluted filter assemblies, where flutes formed in the filter media extend from a first flow face of the filter assembly to a second flow face of the filter assembly, where one flow face is an inlet and one flow face is the outlet. Some embodiments relate to first flute distance between the first flow face and the second flow face differing from a second flute distance between the first flow face and the second flow face by greater than 2 mm. In some embodiments at least one of the first flow face and the second flow face is non-planar, while in other embodiments at both of the first flow face and the second flow face are planar and non-parallel. Other embodiments are described.