Before making your mind don't forget to consider the Europipe integrated system, not just the mufflers. Apart from the upgraded sound you also get 16 bhp. Try some search within Rennteam's threads so you could gain better understanding on the issue.
However, I'm about to cover 2.5k km from Athens to Antwerp combining a EuroTour vacation with a visit to their workshop just to have their system istalled on my 997 C2S.
More info at
http://www.europipe.be/1024.html, click on the video file there as to get a good idea of the stock sound transformation.