Quiet? I picked the FSWERKS exhaust for my car. I was replacing it with the turbo and it was the quietest I could find from my research. 2.5" with a clever straight though muffler design like a magnaflow. Good system, high quality metal, cheap, but they don't polish their exhausts to a shine like COBB does before sending them out. Hence, lower price. I painted mine with silver high-temp exhaust paint. Looks good, protects from salt if I would be living in a rustbelt in the next few years.
Since I looked around there's a few more options. I think there is a "thermal" something or another 3" exhaust that people say is quiet, but I might be misremembering.