The Z51 pack adds more effective cooling for the engine and brakes, different suspension components, stickier tires, and aerodynamic aids that increase downforce. It costs $5000 and can be paired with the optional FE4 Magnetic Selective Ride Control dampers and the Performance Traction Management system for even better racetrack performance.
The car blew me away by futuristic design and pretty affordable price though it's considered a sport car.