I have them on my MBZ E 320. "Quiet" would be an understatement ! You have never experienced anything like this - they are DEAD SILENT. It's like riding on air !! Dry or wet grip is outstanding, as well. But then again, the E 320 is a quiet sedan, I don't drive it like a maniac ( as I do the 968 <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> ) so may be one can appreciate them more on that type of car...
That being said, in spite of the fact they have the sufficient speed rating to take you to the 160mph the 968 is capable of, I was told by many that it would be a pity to put them on the Porsche and that I should instead go for tires which are in the highest, pure all around performance category...so I did. Not sure I am quite happy, but time will tell. I may put the dB S2 on the 968 at some point, after all..
For daily driving and comfort, I would recommend this tire without any reservartions.