Hmmm, mine isn't even close. I have the left and right exhaust manifolds that tie together (at a "y") then a single cat, then the muffler, and a single exhuast out the passenger side behind the rear wheel.

Still, I wonder what a true dual system would do to the EFI system on my van. I don't want problems that the computer can't compensate for. I may just have to go with the aftermarket cat and a better cat back exhaust. It would be cheaper, emissions legal, and simpler. I wonder if I'll really be giving up much power compared to true duals?

I have been looking at the Banks stuff ($$$) and I think I can get my muffler shop to duplicate that work for significantly less.

 

I have a Flowmaster single in dual out and exhaust setup by the shop, you can keep the single design, have the shop tie in a better Y for the front, upsizing the single to a 3" for increasing the flow. I need to have the Y-pipe on mine replaced, the factory one is not equal to both sides, then run a 3" from it to the muffler, or go true duals later, not sure.
I'm not for removal of o2 sensors, if you have one in each pipe, before the cat, just true dual it and add a cat to each side, it'll be fine.