Yes and no.
From my limited knowledge on the subject, the chip you are talking about will be a piggy back ECU. This will take what you tell it at the throttle and modify it to tell the ECU to give more fuel/air than it normally would at that throttle/rpm. However, the 350z has a learning ECU. So it will say "woooah there, you cant have that much sh*t, I'm going to cut back on it cos I know better then you". So the piggy back ECU can tell it all it likes to give a certain air/fuel, but the ECU will eventually tell it to feck off. The only way to get around this is something like a Utec (sp?) which truely controls the system rather than its inputs, but costs big bucks - around the £1500 region to buy and map properly - and gives very little bang for buck.
That's mostly not true at least in open loop ECU mode
Oh well, you can but try
Outcome was still the same, they cant do diddly squat without some serious ECU mods