Here's something that everyone needs to start considering, if you aren't already: Noise pollution is being more and more regulated in communities across the country. Yes, it is difficult to enforce, but it still happens. There is a point at which any reasonable person becomes annoyed by obnoxiously loud exhaust levels, and when enough people become annoyed, local ordinances will be passed and fines will be levied. And typically, whenever something like that has to be legislated, the results are generally more draconian than most riders would like. So it is incumbent upon motorcycle owners/riders to self regulate and install exhaust systems that are not obnoxiously loud...most riders vary in how that is defined, but unless self regulation becomes more the norm, it will be regulated for you, like it or not.
It is one thing to have a Harley that has a nice "rumble" at idle and during acceleration, but it is an entirely different matter when exhaust noise causes car alarms to go off, interrupts conversation, causes people to literally have to put their fingers in their ears, or otherwise causes the average citizen to begin complaining about "bikers" who have loud exhausts. Whether you or I agree with it or not, if the biker community does not begin to consider self regulation, it WILL be done for you, and there is about a 100% probability that you won't like the results.
I am not saying that brand X or brand Y is too loud, because it will not matter what I think, nor what you think...it will matter what those who are offended think, and ultimately what the local enforcement officials think. This is not a political statement, or a statement about what is "right" or what is "wrong"...it is a statement about the reality of what is currently happening across many jurisdictions.
Just some food for thought...