A custom tune will be the best mod you'll ever do to that car. Follow that up with true dual exhaust with some good mufflers (not cheap sh*t, you'll just spend more $ replacing it later) and you'll be set for performance and sound. A cold air intake would be follow those but isn't the best bang for the buck.
Aesthetics that should of came from the factory: 8inch shorty antenna ($20), painted mirror covers ($100), and sequential tail lights ($130).
2010 GT Premium - Automatic - Torch Red