have a look at the ITG Maxogen / Forge Twintake.
Both replace the engine cover entirely.
Yes, to get any decent sound the cover needs to go.
Air is routed through it (theres a flat filter in there) and onto the intake (on the left hand side rear as you look at the engine bay), quite , well packaged (as its a cover AND a filter casing) but also restrictive.
What youve replace with the carbonio is just the bit that feeds air into the engine cover....
Its not quite the same as an induction kit you would fit to other cars, which tend to bolt onto the ManifoldAirFlow sensor housing directly.
On the golf the MAF is also bolted into the engine cover too.
well worth having the cover off if youre diy inclined just to get a feel for whats exactly in the cover