Abstract: A flexible coupler apparatus for joining successive lengths of fluid transmission member in an exhaust system for a vehicle. A pipe inner member is insertingly received in the adjacent ends of two pipe adapter members which are affixed to respective adjacent pipe ends. A first spacer member is radially and axially enclosed between the end of one of the adapter members and the pipe inner member. A second spacer member is radially and axially enclosed between the end of the other of the adapter members and the pipe inner member. A flexible, extensible sealing member mechanically connects the adapter members, and, in turn, the pipe ends. Biasing means are provided for imparting an axial bias or preload to the coupler apparatus, for providing progressive resistance to compression of the coupler apparatus.