The 16 guage are loud enough to prompt complaints from the overly rightous ultra conservative enviromental types, and alert cages to your presence, but not so loud as to overly irritate the neighbors.
Like Daniii, I find that they do not seem loud at speed in a half helmet, but in a full helmet, they are pleanty loud (I could not stand a louder pipe in a Full). Frankly, for me they drone just a tad too much on trips with a Full Helmet. I wear earplugs most of the time (as we all should to protect from hearing loss due to the constant wind noise) and they are fine.
Yes you can set off car alarms with them.
Fred:biker: