I've got a true 2.5" catback from powerflow with discrete tail pipe, I've had people compliment how it sounds, it's definately deeper sounding than my mates 1.8t but I think thats because the tip is facing the ground, but that also means it can be a bit boomy especially as I have a 3" decat and downpipe, but it's not all bad when accelerating slowly around town everyone can hear an unmistakeable turbo whistle very clearly.
All in all sounds droany when Im driving it normally (~1500 rpm) but when it's being pushed it don't sound bad at all can definately hear the wastegate open especially in a tunnel - it screams