Walker was an OEM supplier to Chrysler; years ago I replaced my '69 Roadrunner's original system with Walker pipes (exhaust & tail), and they were identical. I used some NOS mufflers. It's likely that the Walker aftermarket mufflers aren't identical to the factory ones for cost reasons or multiple applications so muffler shops don't have to stock as many variations.
I would expect the OP's car to sound barely louder with OEM-style duals & mufflers than it does now with the single, no drone. You'll be able to hear the motor, but even low radio volumes will be louder than the exhaust.