I second the KMC chain solution. The Red cassette isn't noisy per se, but its hollow structure can magnify noises produced elsewhere (like many carbon wheels also do). The noise originates with the SRAM chain, not the cassette. Shortly after buying into my first Red group, I switched to the KMC X10 SL chain and have been dead silent ever since. Running three bikes that way now. The cheaper and better solution is the KMC chain.