All muscles have that delectable sound. Its one of the things that sets Muscles above the Tuners and exotics. They sound awesome. The way they sound in the game is very close to what they sound like in real life,but how they sound in real life is much cooler. My real Mustang GT has that classic muscle car sound. Its such a turn on. Rocks my world.
In terms of sheer noise,
Ferrari 360 CS > Ford Mustang GT390R
I would bet my life on it.