So, I just got my 07 Touring. I want to "upgrade" it over the next few months. Cash isn't an issue, so I'll do whatever I want to do, but I'm not a kid, so a giant wing on the back is a turn-off, I don't like chrome wheels (I hate their look), and I don't need to announce my presence 20 miles away, so I don't need a 747 sounding exhaust. But here are some of my ideas to improve the car, and I was wondering what other ideas there might be (or improvements to my own ideas).

*Brakes. I want some Brembos, but I can't tell if that's just switching out the calipers, the whole braking system, the discs, or what. I guess I could pay anywhere from a few bucks to huge bucks.
*Exhaust. The NIMSO exhaust system sounds like a good idea.
*Suspension. Not sure if I want to do this, because it might make it much harsher ride than it has now.
*Audio. The BOSE system seems pretty weak. I'd like to get a double-din system, but I don't need Nav, since I have it. Not sure if I can do anything here.

Those are my ideas so far.