My landlord doesn't hear me at all when he is sleeping and I ride up the driveway at night. They seem loud, and yes, they have a bit of volume, but nothing compared to some of the overly loud, bass producing chops of a good ol' school Harley. I don't think our engine noise penetrates into houses too much. It seems loud when you're on it, or right there with it, and no sound barriers, but these engines aren't low frequency, so we're not disturbing many people I don't think. Unless you're full throttle on a small, quiet side street or something, and she's just a screamin! lol. I cruise around half speed, a comfortable RPM for night time neighborhood riding.
I have a normal exhaust stock from the kit. Nothing added.