Well all in all the most important thing to remember on any system is if it's eaisily tunable, and based on your location.. if anyone near by can tune it.
To the person above me, you could pull a data log by using an OpenECU type of system, although I am not sure if they have released Tactrix cables for the 350Z model. Basically, you plug a cord into your OBDII diagnostic port, hook the other end to a laptop, bring up the logging software.. and go for a drive/pull/whatever. It'll save as a file that will allow your tuner to view data from everything the stock ECU has to offer. The great thing about this is, if you find a tuner who is willing to make you some maps on your UTEC, you could send him your base datalogs, and he could send you the map, you could upload it.. drive and log.. send the data back... etc. It may seem complicated but living that far away from a tuner can present some problems. I know, I have an AWD car and we just got our first AWD dyno within 200miles this summer.
Anyhoo.. umm I decided I'd make a compendium of the available tuning software and some of the pros and cons on running them. Coming from the Subaru world, I had quite a few options available, so I've seen almost all that would be available on Nissan applications.
First up is the UTEC..
-Plug and Play
-Map switching on the fly
-9V power input for logging outside of vehicle (racing applications)
-Optional MAP sensor input. Allows for Speed Density air/fuel metering. Important for BOVs, high airflow etc.
-MAF Air metering under cruising loads, switches to Speed density under load (optional)
-250RPM resolution on Fuel and Ignition Timing.
-MAF signal modulation. Can fool the MAF to read +/- 50% it's realtime reading. Good for maxed out MAFs.
-Security Mode.. locks the ECU down making it impossible to jump/bump started.
-Shift Light function
-Solenoid Drivers (Water, Meth, Alky, NOS, etc)
-Online Periodical Software Upgrades
Nice thing about the UTEC is it's speed density metering, which in a nut shell makes it possible (if needed) to run your stock MAF with a boosted application. The MAF sensor will read at off-idle/cruising applications and when you put the pedal down it will switch to Speed Density, allowing for high air-flow rates without pegging the 5v signal on the MAF, making tuning more accurate and there would be no needs for upgraded MAFs.. etc.
Also, switchable maps are nice. I was tuning boost in a friends Subaru with this option and it made driving around town quite a bit eaisier. I wasn't worried about looking like an ass boosting all over the place, I could tone it down through town as long as I switched below a specified RPM. Nice for bad fuels, race/street maps, or if you let your friend/chick/parent drive your car
Next up.. Hasegawa, Kitagawa, and Sigma (HKS)'s FCON V Pro.
-Vehicle Specific Harness
-Lots of options (MAP, IAT, Mixture Controller, Twin Injector Driver etc..)
-Load sense can be MAF, MAP, Velocity, TPS
-Can input any RPM to view
-Can be spliced with a viewer to read anything available (CTS, TPS, IAT, MAP, etc..) Less gauges!
-Integrated Knock sensor
A great comprehensive tunable ECU, the FCON V Pro allows the user to not only program quite a few parameters quite quickly, but view them just as eaisily on a readout, which I think is awesome. As far as switchable maps on the fly.. to my knowledge no. However it does seem to be a more in depth tuning software program, which would make this great for build ups with no base maps available, or for those pushing the limits and need more options. It does not however support supplemental injection, so the drivers will have to be on a seperate unit, and then have those parameters logged into the FCON.
I'll continue with this when I have time I suppose, any owners can feel free to lend a couple of comments.