Finally, a definitive answer from the top! Here is the response from PCNA:

Dear sir,

I am the manager of our Product Planning group at Porsche Cars North America, Peter asked that I respond to you directly with an answer to your question.

The GT3 comes standard with a SPORT button that, when pressed, increases the torque by 18 lb-ft between approximately 3,000 and 4,200 rpm. In addition, the traction control system is set to a more dynamic "sporty" mode.

The Chrono Package adds a lap timer and the stopwatch on the dashboard. If you also order PCM than you can order the Chrono Package Plus which adds lap time storage, performance display to indicate if current lap is faster or slower than a reference lap, remaining laps until empty, and personal memory function (lights, wipers, door locks, A/C settings).

The Chrono Packages are not necessary to get the SPORT button. The order guides will be corrected.

I hope that addresses your question, please let me know if I can be of further assistance.

Best regards,

David Pryor

Manager, Product Planning & Market Research
Porsche Cars North America