Yeah, mine's rarely loud enough to interfere with my phone conversations, and only on a handsfree. It does interfere with my music listening at times, but I'm really into the SQ of my music.
Mine is at its loudest (and booming enough to be irritating to me) when I'm off the gas and engine braking on a long downhill grade anywhere near 3k rpms. With the many hills around here, that's more often than I'd like. I find myself throwing it in the next higher gear or in neutral and just using the brakes when going downhill in my subdivision late at night out of respect for my neighbors. When my fiancee is on our back deck at night, she can hear me coming about 3/8 mi. away or so.
Mine also seems loud when under certain throttle/load/rpm situations in 1st through 3rd gears. Usually light throttle, medium load (uphill) and also in that 2.5k-3.5k rpm range seems to do it. As soon as I hit 4th, it's fine. On the highway at 70-80 mph is tolerable if the terrain is pretty flat, but even then it can wear on me after the first hour or so.
Would I still recommend it? Hell yeah. It's a great product. And it could be that mine is just a hair louder than most for some reason, like QC variations in the mufflers. I don't think it's just my ears though, when my fiancee, friends, family and neighbors all comment that it's fairly loud. What's ironic is that when I was standing about 20 ft. behind my car during my dyno pulls, it didn't seem all that loud. It's a lot like my Trans Am...it's only under certain conditions that it gets that booming going.