This disclosure provides an exhaust flow detection and variable dosing system and method for treating exhaust flow from an engine. The system includes first and second exhaust flow legs, a cross passage connecting these legs upstream of SCRs and a sensor positioned along the cross passage to detect at least one of differential pressure between the exhaust flow legs, and exhaust flow in the cross passage. A dosing circuit connects a dosing treatment supply to each of the exhaust flow legs at or upstream of the SCRs, and at least one dosing device positioned along the dosing circuit to control the amount of the dosing agent delivered to each exhaust leg. An electronic control unit controls the amount of a dosing agent delivered to the exhaust flow legs independently based on exhaust flows determined for each leg using at least one of the differential pressure and cross passage exhaust flow.