That dump valve in your link is atmospheric (which means when you lift of the gas, it dumps the air into the engine bay). Our Golfs have recirculating dump valves, which puts some of the air back into the turbo system to help it spool up again (I think).
That also helps explain the difference in noise. Some people can fit atmospheric DV (I think most success is on the AGU engines) with little or no problems, but if the car was designed to have a recirculating valve, it is far better to stay with that system as the car will think something is wrong and throw up error codes.