Tuning a Ferrari... expensive, but not uncommon.
There is a new tuning package for Ferrari 599 GTO by Romeo Ferraris tuner.
For achieving the power they imagined, they will install high-flow air filter and new sport exhaust system on your 599 GTO. This will resolve in engine producing 676 hp and 633 Nm of torque. This is 15 hp and 13 Nm more then the standard 599 GTO.
There is also Stage 2 package for even more power, if you don't find 676 hp satisfying. With diffrent exhaust system and ECU remap, you can get 700 hp in your super car. This adds 40 hp and 48 Nm of torque to 6.0-liter V12 engine.