I've got an '04 G35 Sedan and skipped on the factory sat radio after having it in a loaner car. Why? The display on the radio really sucks since it's 1 line. Especially after you get used to the multi-line displays on most radios today.
But it is a cleaner install.
Here's a place that has them - they sponsor the
www.freshalloy.com site (great site for Nissan enthusiasts).
www.grubbsperformance.com
The radio is here:
http://www.grubbsperformance.com/servlet/Detail?no=2905
$199
I believe that all Nissan's radios from the 03-05's are the same.
Hope this helps.