Well, I'm not sure the rims are black.
I actually think they're slate grey.
The GT2 body kit isn't officially available from Porsche for the 996 Turbo but several Tuners are offering an aftermarket install. Watch out: some Tuners are stupid enough not to modify the position of the front watercooler and therefore do the install wrong in a way or another. This can result in some nasty consequences, for the driver (aerodynamics) and engine (cooling).
The "GT2 kit" isn't cheap but seems to slightly improve stability at very high speeds. For street use, the "GT2 kit" is actually pretty useless.