The first version, which is still available, was simply a cut off oem pipe along with the hose and larger diameter turbo outlet.
But there is a second version utilizing a round pipe, and the rest is the same as with the first version;
http://www.redline-motorworks.com/Neuspeed_Hi_Flo_Turbo_Discharge_Conversion_Mk5_GTI_p/48.02.65.htmThis mod by itself, or with minor K03 mods, will leave you noticing no substantial power gain.
For myself I've classified mods into two categories. Power mods and enhancement mods.
1) Power mods, such as ecu remaps, fueling, and bigger turbos etc., are mods that will increase the size of the smile on your face. You know for sure that there is more power under the bonnet.
2) Enhancement mods, like turbo discharge and downpipe etc., are mods that will allow the power mods to give all that they can. These all together will free up a bit of horsepower when added to cars that have big power mods on them, but very difficult to feel the difference on cars that do not have very many power mods on them.