What is your current setup?
Low tone for me would be manifolds, 2" or 2.25" pipe, maybe an H pipe if you can fab it up, and some LONG turbo mufflers.
For reference, here's a video of my old Bronco - running long tube headers, 302, H pipe, 2.5" pipe and summit turbo mufflers. A bit louder than "low tone" but no where near as loud as some of the others I've owned.
[youtube]njlFsDiG0xw[/youtube]