The NAV option is a *factory only* option, ie not available for dealer
install. It is available only on the Touring model, because it only works
through the Touring model's Bose audio system. It lists for $2,000
when ordered from the factory with the car.

Got it on my car (a 2004 Touring roadster, Daytona Blue with Frost
leather interior). It is very nice, *much* better than any of the aftermarket
systems I've checked out. It is highly integrated with the car (talks to
the wheel sensors among other things), so it goes to dead reckoning
navigation when driving in places with poor GPS availability. I don't think
any aftermarket system does that (they just go stupid when they can't
get a signal from the satellites).

The necessary wiring harness will not be present in a Touring ordered
without NAV (that's what Nissan says). There are several harness issues,
GPS antenna, connection to the map database DVD player behind the
driver's seat, connection to the car's CAN system for dead reckoning
ability, and voice navigation integration with the Bose system. So
a dealer install would be more than just plug and play. They'd have to
rip into the car to install all the various pieces, and run a new harness
too. It is technically possible, but difficult, and likely quite expensive
to do properly.

If they can do it for $1600, she isn't getting ripped off. But I doubt they
can, that's $400 below factory, and the factory doesn't have to tear the
car apart to install it. I suspect the salesman was just trying to sell her
the car that they had on the lot, and told her anything, true or not, to
make the deal.

There are aftermarket NAV systems, several are cheaper than
the factory system. They can't integrate with the Bose system, but
that system sucks anyway, and you'd probably want to replace it
too if you decided to go aftermarket.

(The only reason I haven't replaced the Bose in my car is the tight
integration with the factory NAV, which I really like. I'm just going
to replace the amps and speakers, and add an outboard EQ in an
attempt to find some midrange, leaving the HU as is because I
don't want to lose that integration with the factory NAV.)

Spoilers are a different matter. That's a fairly simple body shop job.
The dealer can do that easily and cheaply.  But get his promise to
do it in writing.

Keep in mind that the aftermarket has a slew of different spoilers
and partial or full body kits to choose from. Some of them are more
attractive (IMHO) than what the factory offers (but some are pure
ricer boy). None of them are particularly functional.

The car already understeers, adding a rear spoiler that *worked*
would just make it worse. Fortunately, most of them don't work.
If you like the look, fine, otherwise forget about it.

(Adding a front spoiler lower than stock just ensures you'll be a
steady customer of the body shop.)

If you want something real to improve handling, get a set of
aftermarket adjustable sway bars, and wider front tires. That's
the most bang for the buck you can do to this car.

You're going to be replacing front tires often anyway, due to
the tire feathering issue with the 350Z.

350EVO's new adjustable upper control arms can potentially
fix that problem (excessive negative camber), but that's another
800 bucks, and the negative camber does help cornering on
the track.

Gary