I just installed mine today. You can definitely hear the difference, and the install is rreally easy. My BOV isnt really that much louder, but you can hear the turbo spool up like 10x better.
i've actually noticed some fluttering too....it sounds to me like the BOV(because it only does it when i let off the gas)...it prolly always fluttered..but it's more pronounced now because of the sri.
you'll love the sound of it, sounds awesome and YES you can hear the stock surge valve so much more and the turbo spooling up sounds like a jet taking off i love it.
flutterings there u get used to it its a turbo car after all all the noises are cool imo also at least hte perrin sri sounds a like a bov itself sometimes when u shift