THe big majority of the aftermarket body kits do nothing to affect aerodynamics, at least not on a visible scale. A splitter will do much more, since it will cut the air more efficiently and force it over the top and speed up the (less of it) air under car lowering the pressure thus sucking the car down. Yes, the spoilr on the back does make a big difference, especially at high speeds. But i just can not imagine the XRT without it. Call me a rice boy, i don't care, i know i'm not.
About the drifting, i did it for over 2 years (started at the end of 2003, on Xmas, with a keyboard, got a wheel and S2 in spring 2004). I quit just because of the thing you say you know very well - the society. Everybody wants body kits, mroe power, more steering angle, better tires, etc. Why can all the old school guys drift like nothing happened? Oh, nothing did happen. And they just pwn. That's the thing. Take a look at CObalt BLue for example (used to be in nsane, dunno where he's now). Take a look at some SWC (if they still exist) or Saiko D guys. THey did the things the same 3 years ago.