Yes you need a recirculating valve. (diverter valve)
'Dump' valves do not agree with VAG 1.8T engines. Many people say they have run these ok with no faults, but there are unseen issues.
The most popular DV on here is the Forge 007p recirculating valve.
If you are after more noise Forge now offer an alternative which is partially recirculating and atmospheric. (Forge split R)
There was a group buy on these but i think its closed as it was a limited number thing.
The forge valves are fant astic quality, so they will cost a bit.
If you think this is too much then keep an eye on the for sale section, they often come up second hand for £50 and they have a lifetime warranty
as for the chattering sound, you wont get it. The fact that you need a recirculating one prevents this.
PS, i think this thread will get a few sarky replies, dont take it to heart, its just that this sort of DV question is VERY common on here. Try the search function out and take a look around the site and im sure you will find it very useful in the future.
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