Bose and Nissan have a weird relationship, by the way. Bose is supposed to be known for measuring the acoustics in a car and then developing a speaker package to match, but... Nissan is also known for lots and lots of mechanical noise across their entire model line
You expect a lot of road noise in a Z, but even in something reasonably tame like a Maxima you can hear a lot more rattling and other noises than you would expect from a modern sedan. Bose didn't put in its Active Noise Control feature in this car, which uses a microphone to cancel out road nosie. GT-R and competing Porsche models have that, but not Z :-\
You might need some sound dampening material to get your money's worth out of the "premium audio" package. For me, it just came with the Tech package so I didn't really care that the car's so noisy you might never notice the difference between Bose and base speakers. I _really_ wanted the auto-dimming mirror, reverse camera and navigation system w/ traffic data through Sirius/XM.