There are three specifications of 350z
03-05 is DE
06 is the rev up I think which offers slightly more power than DE
07-09 is the HR (309bhp, bonnet bulge, twin air intake, 7500 rpm)
And then you have the GT pack which is a factory extra (cruise control, Ray's, heated leather seats ect)
I'm not the most knowledgeable about Z's as I haven't owned one for long so if anyone has to correct me few free
Just wanted to give you the heads up on the common low oil pressure fault as I didn't factor in for spending £800 after purchasing my Z, as well as the higher tax for the HR (£530 mine is, just incase you weren't aware of that)
Hope this helps a bit, like I said there may be things I have missed or may not be 100% correct as some 07 cars are not HR and have the Rev up engine.