I used to have rust outs, that's why I replaced the whole exhaust system. They give a nice loud exhaust note, but just dont look as cool!

Back on topic tho, I've had great luck with the sound and material quality of MagnaFlow mufflers.
There's also a couple types like the Thrush Turbo series that have a nice mild note at idle and while cruising, but when you put your foot in it it livens up real nice. I had them on my '65 3/4 ton behind a 327, almost couldn't hear it running at idle, but when I got into it EVERYONE knew it.