1. The 370 is louder than the 04 Altima 3.5 I upgraded from for the most obvious of reasons, but even that car wasn't "quiet." Edmunds must be looking for highway lux and long distance comfort, b/c I would imagine that most buyers of larger engines in their class and sportier cars want a little something from the engine and exhaust system as part of the driving experience.
2. I'll take a moderately and pleasantly loud Z over the neighbor's raspy fartcan any day of the week
3. I don't have Sport upgrade and I'm guessing my 18 wheel tire package would be somewhat quieter than the 19s to start. But, will soon see how a CB will change that up...