i have 2006 300 3.5l v6 touring, with a cat problem code. I am having a hard time finding a replacement converter because both of my manifolds exhaust merge into one single pipe which leads into one single muffler and exits out into one single end.

all I am finding out there for replacements are two separate exhaust cat pipes which look like I will need two new mufflers. this is going to be costly if done this way, i don't need to replace both cats just one and it seems I am being forced into replacing both sides is there a workaround and or why do I only have one muffler? why can i not find my cars exact muffler set up?