I am not a loud pipe guy. I have had v-twins with straight loud pipes and while it was fun for a while, it gets annoying on longer trips. I will agree that a snap of the throttle gets attention quick with loud pipes however and is easier and faster than fumbling for the horn if something catches you off guard.
I much prefer things a little quieter and have figured out a long time ago that you simply have to assume every driver is about to do something stupid and you will be right about 70% of the time. Overly loud pipes ripping through a populated area is ridiculous and annoying. There are in between pipes that are not loud for loud's sake and offer a nice tuned exhaust-nothing wrong with that as long as you control the noise output around others. Personally I enjoy the quiet and have even used noise isolating earbuds for riding and listening to music under my helmet. I become much more visually aware and take extra care and feel perfectly safe. I have heard the loud pipes saves lives mantra too often from the same people who refuse to wear a helemt or protective gear or argue that somehow you will be safer without one (a helmet)so your head doesn't get ripped off or some such thing. Not trying to start a helmet debate-do what you want it's your head. Just pointing out the obvious logic flaw in many "loud pipes save lives" people that ride in helmetless, drunk or in bathing suits and sandals or just about.
It's your bike-do what you want. Just remember that loud pipes are annoying to every other person that doesn't have em and really aren't the key to safety.