A gas turbine includes a turbine and an axial-radial diffuser. The turbine includes a last stage airfoil section, which includes a first inner annular wall, a plurality of airfoils, a tip shroud including a first outer annular wall, and a stationary shroud including a second outer annular wall. The first inner annular wall is angled at a first inner angle average, the first outer annular wall is angled at a first outer angle average, and the second outer annular wall is angled at a second outer angle average. The axial-radial diffuser includes a third inner annular wall and a third outer annular wall, wherein the first diffuser section is disposed immediately downstream from the last stage airfoil section, wherein the third inner annular wall is angled at a third inner angle average, and the third outer annular wall is angled at a third outer angle average. The first outer angle average is greater than the third outer angle average, the first inner angle average is greater than the third inner angle average, and the third outer angle average is greater than the second outer angle average.