In a multi-cylinder internal combustion engine including an exhaust gas turbocharger to which at least two separate exhaust lines extend from different groups of cylinders of the engine, the exhaust lines have discharge openings arranged adjacent one another along a control surface area and a control slide member supported so as to be movable relative to the exhaust gas discharge openings includes wall portions movable with the slide member between a position in which the wall portions of the slide member are in alignment with stationary wall portions between the discharge openings for maintaining the exhaust gas flow passages separated from one another and a position in which the wall portions on the slide member are out of alignment with the stationary wall portions, wherein the exhaust gas lines are in communication with one another.