An exemplary diffuser includes a plurality of air flow channels defined by a corresponding plurality of vanes. The vanes extend from a first side of the diffuser and define a width of the air flow channel between the corresponding plurality of vanes. The first side has at least one tapered surface extending from an inner radial position to an outer radial position. The distance between a tapered surface and a top side of the plurality of the vanes defines a depth of the air flow channel. The width of the air flow channel varies relative to the depth of the air flow channel along the length of the air flow channel.