I was planning on getting a Z, but after test driving a car with the problem and knowing that Nissan wouldn't acknowledge the issue, I decided to keep my money. The sound was so bad it hurt my ears, even for a period of an hour or more after I got out of the car. I have better things to spend my money on than a gamble on a car that the manufacturer won't back up. It still looks like Nissan and it's dealerships are giving people the run around in some cases. It's really unfortunate because the car is just awesome otherwise.
I've posted this before, but for those who want to know what it sounds like, here it is.
freesound :: view sample :: TONE 10 kHz 44.1 16bit.wav
Look for and click on the little black triangle and turn up the volume. Hurts, huh?