muffler(s) on a Slant Six?

My old dart had a flowmaster 60 series off a jeep, didn't drone too badly, and had a very exotic engine sound at the back. My dart now has a 2.5" Raptor muffler, it's got a very low rumble, some drone under throttle, but is quieter than road noise while you're coasting.

My engines both were dead stock though, through the manifold.