I don't know if my variations will translate - I have done 2in/2out mufflers, but not a cat. I have been unhappy with a 2in/2out arrangement. Largely for noise, but I believe low end and mid range performance has suffered as well. No proof though. I suspect there would be a better way, but you won't know if you don't try.
If you must preserve a cat, perhaps try 2 separate smaller ones and do not cross lines.
This is a new one for the CEG. Anyone else got any thoughts?
Mark
