Nope, k04. The differance is the that inducer and exducer are a couple millimeters larger on the rs6 than the rs4, but the biggest gain is that the hotside housing is larger. On the rs4 they are k04-25 and 26, on the rs6 they are k04-27 and 28
they are also modified to be a bolt on, can't just take them off an rs6 and put them on an s4/rs4