i have the understanding that BOV only works while u change
gears, like 2 gear in transition to 3rd, or 3rd to 4th. It is only
when the pressure is off the petrol and cluth is stepped, then the
BOV kicks off the pressure. dun think it will cause turbo lag. this
is the understanding from driving my friend's TC car.
Dun really know what other effects it have except for letting of
the pressure. Only that it sounds sweet.... 
