Hi,
I have the factory valve and with a pod filter, it makes the BOV noise but not flutter. If you search for it on most forums, you'll find that the flutter is a bad noise. Some people claim its the HKS SSQV while the believe the majority believe that valves are adjusted incorrectly causing turbo surge. Either way, its up to you whether you still want to go ahead.
You can try the forums for BOV's or places like autobarn etc or if you can wait, try www.nengun.com if you want to get it cheap and can install it yourself.