EXHAUST COLLECTOR SYSTEM AND INSTALLATION METHOD

A system includes an exhaust collector tunnel (32) configured to mount inside an exhaust collector (30) of a gas turbine (12). The exhaust collector tunnel (32) has a tunnel wall (33) configured to extend around a turbine shaft (17, 19) of the gas turbine (12). The tunnel wall (33) has a variable diameter (98) along at least a portion of a length of the exhaust collector tunnel (32).