Not to be a jerk, but google should be able to answer this one. Two good threads to start...but there are many more.
The BIG BOV thread
BOV FAQ_from NASIOC
Basically don't do a full vent to atmosphere. It won't run that rich, but its pointless unless you're running really high boost. If you must have a vent to atmosphere, go with a 50/50. If all you want is the woosh (plus turbo spool noises), go with an intake. There are tons of BOV threads. I can't remember them all but they are pretty easy to find.