An exhaust system includes a first exhaust after-treatment system receiving exhaust gases generated by an engine, a second exhaust after-treatment system downstream of the first exhaust after-treatment system, and at least one bypass connecting an engine outlet to an inlet to the second exhaust after-treatment system. A turbocharger is associated with the bypass and a bypass valve is located upstream of the turbocharger. The bypass valve is moveable between an open position to bypass exhaust gas flow to the first exhaust after-treatment system, a closed position to direct all exhaust gas flow to the first exhaust after-treatment system, and a partially open position where one portion of exhaust gas flow is directed into the first exhaust after-treatment system and a remaining portion of exhaust gas flow is directed into the turbocharger. A controller controls movement of the bypass valve between the open, closed, and partially open positions.