I have a 2007 Lincoln Mark LT, it has duals from the muffler back I wanted to put a Dyno-Flow Muffler on which would be just one muffler. Out of curiosity I asked the mechanic about dual from the engi...
I think maybe it can be done but is a complex and expensive operation probably not worth it for the gains. You probably know that duals from the muffler back are pretty much fake and just for looks although I did it just for fun on a Chevy truck. You might gain a few horsepower but it's mostly for looks. I think the sound and a little less backpressure comes from the muffler used and not by having 2 pipes.