A gas turbine exhaust diffuser is configured to be at least partially disposed within an exhaust collector. The diffuser also includes an inner wall configured to extend to a back wall of the exhaust collector, an outer wall circumferentially disposed about the inner wall along a portion of the collector, and an inlet between the upstream end of the inner and outer walls. The inlet is configured to receive an exhaust flow from a gas turbine engine. An outlet for the exhaust is located between the inner wall and a downstream end of the outer wall. The outer wall is asymmetrically shaped so that an opening between the outlet and the back wall of the exhaust collector is larger on a first lateral side of the diffuser adjacent an exhaust exit of the collector than an opposite lateral side of the diffuser.