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...
When I did the "duals" on my 2000 Chevy, towing a 5th wheel, wife really did not like the exhaust drone even though the pipes pointed out to the sides. Looking back now, I would have to say it was a throw back to youth type of action that wasn't worth the noise, cost and very little HP gain. Also, you throw away the stock muffler which is very long life these days.