Why is one exhaust directed upwards?
The rotation direction of the propellers produces a rotating slipstream.  This slipstream pushes the exaust from the (engine's) right side downward, but the exhaust on the other side would be pushed up, producing potential heat problems where it impinges on the wing (as well as depositing lots of soot).  By bending the exhaust pipe upward as you see, the exhaust on that side passes over the wing, in an airstream that will both protect the wing surface from the exhaust heat and reduce soot deposition.