From a dealership's view, they have to buy over $100,000 in diagnostic tools and computers specific to the GT-R. Also, mechanics have to be put through a 2-3 month training course to be certified to work on these animals.
So if you hear somebody has one in the Caribbean, they are either lieing, or they ship the car to the states for servicing.
For GT-R owners in Japan, and possibly the US in the future, if they go to race their car at a Nissan certified track, the GPS unit in the GT-R will either remove, or extend the factory rev limits. After you have finished flogging the car, you have approximately 48hours to get to a dealership so that they can perform a $1000.00 service to reset the vehicle. If you fail to do so, your warranty will be void.