About two weeks ago I ordered a Milltek Non-Resonated exhaust from Stratmosphere. The people at stratmosphere were very accomodating. I had the exhaust put on about a week ago and it sounds amazing. I listened to a lot of audio clips and it sounds to be the most promising exhaust yet for the Audi S5 and no I'm not just saying that because I had it put on my car. If you have a stock Audi S5, I strongly recommend putting an exhaust on the car because I gained approximately 15-20 bhp and the car just sounds amazing. Every tech at my Audi dealership came out to hear the car after the exhaust and said it was probably the best investment that I could have made on the car. I plan to get some audio of the exhaust up on youtube soon and I will post a link ASAP. I did have some short audio already recorded but I didnt have a full launch and so it doesnt do the exhaust justice. I will try to post within the next day or two.