A gas turbine engine comprises a main gas path having an inner flow boundary wall and an outer flow boundary wall. A turbine exhaust case inner body defines a portion of the inner flow boundary wall of the main gas path. A lobed exhaust mixer defines a portion of the outer flow boundary wall of the main gas path. A stiffener ring is interconnected to at least a number lobes of the lobed exhaust mixer by a plurality of circumferentially spaced-apart struts extending through the main gas path. The stiffener ring is attached to the turbine exhaust case inner body by flexible features, such as circumferentially spaced-apart spring blades.