Do i really need a BOV???
Most turbos do not come with anti-surge covers and anti-surge covers actually decrease efficiency slightly so some people stray away from then unless necessary on their setup. Anti-surge covers aren't designed vent off air during deceleration like when you run without a bov although they may work for that. The are designed to stop 'real' compressor surge during acceleration when the turbo/motor setup creates a condition that leads the turbo into the left side (surge side) of a compressor map.
New turbos, especially ball bearing, can handle a lot more abuse without a bov.

I'd say low boost is ok with no bov but high boost should have one. Some air is going to go into the engine, even with the throttle shut, some is going to bleed out the air filter.
thanks robby






