I have dual BOV's and specified to have Sam at GTM use the Synchronic versions which have the option to recirculate back into the pre-intake with 1.25" hoses. Sam made this modification and the sound is negligible.
I also have the waste gates plumbed back into the exhaust. The whole car is stealth in this regard. My sig shows it's still effective.
That's what I recommend.
Coop