I think this topic came up before. But I'll repeat. Cast iron black pipes, 1-1/4", front-to-back fitted together with assorted elbows, unions & never-seez. No mufflers, baffles or other needless constrictions other than the pipe id itself. Sounds pretty good & mellow to me. Also use a similar 1-1/2" black pipe setup on an SBC with equally pleasing sounds...to me anyway. 8^)
Jack E/NJ