Are you considering using them on your S4? Do you know if the package will physically fit? From what i've read, the RS4 has different front knuckles so may use a different damper design.
Either way, to answer your question.. Dampers and springs are specially designed for every car.. as soon as you change it, or put it on something else, it will technically be 'wrong'.. Eg, the unsprung weight will most likely change, affecting the wheel frequency, which ultimately means the damp/rebound/spring shock absorber package won't be as good as it could be..