Unfortunately in the USA and Australia the MK8 didn't get the nice "Clubsport" style rear muffler like they did in the EU. So we are stuck with one similar to the MK7 and MK7.5 - a poor sounding one.
Luckily there are OEM solutions. One being the MK8 Clubsport unit with matching valance. Or this, the Euro GTI muffler with normal sized tips which means you don't need the extra valance to match. The benefit here is cheaper shipping.
For Australian delivered MK8 GTI's it will require modification to the factory mid-pipe as the Australian delivered GTI's have a 55mm exhaust instead of 65mm in other markets. I suggest taking it to an exhaust shop for fitment.