A flow diffuser for vehicles of the type having an engine and an exhaust pipe generally includes a body including a plurality of inner diffusion ports extending through the body, wherein the body may be attached to an exhaust pipe at or near the exit plane of the exhaust pipe, wherein the body is sized to have a cross-sectional area that is smaller than the cross-sectional area of the exit plane of the exhaust pipe to create a plurality of outer diffusion ports around at least a portion of the outer perimeter of the body when coupled to the exhaust pipe, and one or more extension flaps extending from at least a portion of the outer perimeter of the body.