My Jeep is a bit noisy (re-done y-pipe, high flow cat, Flowmaster 70, all 3" pipe from the y-merge back). However, it's not terribly loud, and is reasonably quiet if I'm gentle on the throttle or at idle. I always try to be quiet coming in and out of my neighborhood, especially early mornings or late nights.
Fortunately, it's got a pretty smooth tone, so it's not too disturbing. Even my mom, who complains about pretty much any loud exhaust, doesn't mind the sound.
1998 Jeep Grand Cherokee 5.9 Limited with lots of mods (207k miles, bought with 100k in 1/2010)
Rotella T6 @ 6k OCI