When an ear-shattering loud bike goes past me or in my neighborhood, it is usually a HD. I find it very annoying. I really don't like it that way on any bike. I think it's about time somebody steps up to the plate to quiet these guys down. A friend has an HD with pipes so loud I can't even stand next to it at a stoplight. Why bother with pipes? Just leave the whole exhaust off.
Of course, my opinion goes against the "holy grail" of "loud pipes save lives", etc. Whatever, the stock pipes are just fine if that will keep a lower profile. If you have the loud pipes, then I have to be ahead of you or waaaay behind you to hear myself think.