If someone has a "straight through" then by definition it has no boxes surely?
As mentioned before it depends on the car, the owner and what they like. Mine has a strange resonation just under 2000rpm but as I am never at that exact revs for a long period of time it is not a bother to me.
Under normal driving conditions while it's very loud outside the car, inside it's actually relatively quiet, especially on an open road. However yes from outside or houses then people are probably making threads on forums on the internet complaining about it.
I've done several 3+ hour drives with the exhaust on mine (since the turbo upgrade) and never once have I yet felt it was annoying. At 80mph on cruise it's hardly any quieter than normal until you open it up..