A Milltek on the mk4 R32 was pretty much a necessity due to the OEM system droning. The res version I fitted was similar to stock on the inside (without the drone), and made the 'R32' sound slightly more pronounced on the outside.
I then had a non res Milltek on the Edition 30 which was too loud/droning on the motorway (although nice at other times), then the res version which was basically the same as the OEM if not quieter.
As far as the mk5 R32 goes I think the stock system is very nice and louder then than the res Milltek on a mk4 R32 was, I am guessing the res Milltek will sound much the same. Non res Milltek on a mk5 is very loud iirc.
all imo