it goes by the inlet and outlet size of the pipes.
I think it's 2.5 " inlet and dual 3" outlet, something like that.
any reputable muffler shop can clarify that or if not mock it up at the shop and get it installed.
2012 CC | HEMI
Performance: Solo Perf. C/B | K&N
Exterior:13+ Projectors | Rampage LED Bar | Sonar LED Tails
Suspension: Belltech 963SP | Falken 305-45-22 | RT Replicas | Hellwig 7709