63 dart exhaust

You don't "pick up" exhaust pipe pieces for a '63 Dart any more -- you have them made by a good custom exhaust shop (not a chain place like Midas or Meineke or Speedy, etc.). The tiny-diameter pipes were original equipment for three reasons:

1. They were cheap
2. They were cheap
3. They were cheap

If you're smart, you upgrade to a 2¼" headpipe as the factory did in '76 for freer breathing with resultant better driveability, performance, and economy. If you want to approximate the stock-type (quiet at all speeds) exhaust note while improving engine breathing, use a larger-than-original, premium OE replacement grade stock-type muffler in the 4¾" × 9¼" oval size, such as a Walker #21110 or AP-Goerlich #2086 -- rather than any kind of a "turbo" or "high performance" muffler. Any good exhaust shop will be able to order in either of the specified mufflers, or you can buy them online from rockauto.com or in person at any local NAPA.