Hi, Eric.
The first step I would recommend is to "chip your head".
Most of our cars already exceed our ability to drive them - get into a performance driving school pronto! The local BMW chapter here in the Puget Sound has a fabulous program - my son and I have been going for the last 5 years, and I am just beginning to catch up with my car (figuratively). I strongly suspect *your* chapter is similar.
That said, it is a hoot to modify these cars to suit our driving 'requirements'. Don't get caught up in the game of having the longest list of mods in your sig; give some thought to what you want to do with your car, and work to fulfill your plan.
For my money for a daily driver, I get the most enjoyment out of a short shifter, and heavier sway bars. I like to corner flat, but don't need to jounce my kidneys with a Bilstein Sport and Eibach combo, which I have done before. I would follow that with a chip - the rest of the hp upgrades are subtle and expensive. If you go the route of the SC, you will drastically shorten the life of your engine (like Wayne said!) and you'll never get the $$$ back out of it.
Just my thoughts, Larry F.