An exhaust after-treatment system for treating an exhaust produced by an engine, including an exhaust passage in communication with the engine; an injector for dosing an exhaust treatment fluid into the exhaust passage, a mixing device positioned downstream from the injector, the mixing device operable to intermingle the exhaust treatment fluid and the exhaust; an irregularly-shaped exhaust treatment substrate positioned downstream from the mixing device; and a dispersion device positioned between the mixing device and the irregularly-shaped exhaust treatment substrate. The dispersion device includes a plurality of dispersion members each being operable to direct an exhaust stream flowing through the dispersion device into a plurality of different directions to disperse the exhaust flow over substantially an entire surface of the irregularly-shaped exhaust treatment substrate.