If you increase the valve pressure (turn in the screw), you increase the valve's resistance to opening at lower vacuum levels, meaning part throttle or at idle but you also increase the occurrence of compressor surge, which is what a BOV is there to prevent in the first place.
Toyota MRS 00/05
Car make: Toyota
Model: MRS
cc: 1.8cc
Color: Red
Type:Convertible
Mileage: 60k+
Extra: TRD stage1 bodykits, Pioneer player, Latest type tail lights
Location: JB
Import by Mutiara Motor