Used to own a MkiV R32 for 5yrs. I had replaced the OEM with a blue flame Cat back system. The MkiV tended to groan when you were driving along and since getting the S3, its actually quite refreshing having a car that is relatively quiet when your driving normal.
My question is that since you have replced your exhausts, do you notice much or any difference inside when your driving? I like to hear a bit of a rip from an exhaust but wouldnt want a constant droan when driving