WoB, hope this will be taken in the spirit it is intended. In your lucky position and at your age I would recommend that instead of putting the $2K into parts to make your car faster, you spend it on educating you to drive even better. There are several performance driving schools as well as local Porsche Chapters' Driver's Ed/Autocross events that would fit well within your budget and produce a better outcome than bolting on various bits of plastic and metal, etc. The stock Boxster has more performance than most people's skill can ever use. It has been estimated that most people don't drive these cars to more than 60% of their potential performance. So one way of thinking about it is you could get a ~35% performance gain (40% would be going to the edge a bit) by improving the driver's skills to utilize the full performance of the car vs. changing the car itself in some way.
Also, this is an investment that you get to take with you when you change cars later and doesn't depreciate like the car and accessories will.
I've done the local autocross "school" and a driver's ed event and it made me a faster, safer driver (and I'd had a few years more of practice up to that point than you
). You'll learn to carry more speed through corners and how to stop better, etc.
BTW, if you need new tires, that $2K could already have found a new home...