Your idea of piracy is very good mate, but i am more then sure that it will not work as those new maps will be encrypted as well and need firmware update as well to run new maps. That's why or rather how Al Futtaim makes 3000 per update, or else dealers can also sell updated DVD for 1000 AED.
However I love to be proven wrong here, if you manage to do this successfully let me know i have something else in mind for my Lexus too and we can share the cost.