Audi modified the suspension parts and settings along with the adding the spoiler and ASR (later ESP) after early TT crashes early in its release, the 1999 Euro models. Originals had problems swapping ends when drivers would lift at high speed, the ducktail eliminates the lift created by the downward curve of the hatchlid. Lifting causes the rear end to float, somewhat because of weight distribution, mostly because of bad aerodynamics, and occurs when the engine is no longer propelling the car under throttle. The steering/suspension was changed because it was "sensitive," though I personally think that issue was overblown, as the TT lost road feel as a result. This may also be the reason rear camber cannot be properly adjusted on the rear OEM control arms.