I'd say it's better to have it already on the car. I have a 2011 GT
with the brembo package and I like it a lot. The brakes alone are worth the price of the package. I had Stoptechs on my Audi, which I had before this car and they made a world of difference. Not as much on the street, but a big difference on the track. I would say that you should drive one with the track pack and see if you like it. If you don't then you can put that money toward other options that will be more appealing to you.