noise seems come from rear diff when I shift, I mean.

 

exact same noises in my 07, its normal. Have you ever noticed that a garage amplifies noises? Something about a concrete room with bare walls... ever rev your car in a tunnel or parking garage, honk your horn, or shut a door? Its all louder. Definately paranoid.

 

dealership time

 

I have an 03 Z with the same shifting noises and that "poping" noise from the rear axle.

geez, it's a relief knowing that all these noises are "normal" and nevertheless happen many others... how ironic...

 

Ummm I just bought a 2007 350z also and I dont have any noise like that WHATSOEVER.

I dont think that is normal since other cars dont do it?
Ask around at other dealerships also maybe?

 

How fast do you release the clutch? Just ease that clutch out...sounds like you are droppin' it. I don't think my car is that loud, but then again I never heard it from the outside shifting.

 

hmmm... I have an '07 w/ 3K miles. I don't have that popping noise. I think it is strange that some Z's have it, while others do not. I'd keep checking around.