I can honestly say that the Milltek is the most superior exhaust in fitment, sound quality, and performance I've seen.
So sure they've done a good job of it, Milltek invited two of the World's most influential automotive magazines to test it. You can see what they think below:
Top Gear magazine: April 2014 - Read the full article online
EVO magazine: April 2014 - download the article as a PDF