you will not make any more POWER in the form of HP from a BOV..


HOWEVER.. When you shift gears in a car without a bov or bypass valve (take for example my old 1988 300zx turbo) the turbine is first going forewards creating 14 lbs boost... then you close the throttle and put in the clutch...

All this air stopps and rushes back towards the turbine, hits it, and spins it many thousands of rpm in the WRONG DIRECTION!!!

Then when you get back on the gas, your motor has to take the time to push the turbine back in the RIGHT direction before the turbo can produce boost again.....


with a bov, all this air goes into the atmosphere, and the turbo continues to turn in the INTENDED direction, not having to take the time to REVERSE and then go forewards again...

The performance boost in a bov comes with the response of a turbo after the shift, with a bov or bypass valve, you will return to boost in a much shorter time after the shift....


This also goes for times when you let off the throttle and are not shifting......................

Power returns FASTER because the turbine does not have to accelerate to its boosting rpm's again..... (or return from reversed RPM's in the case of NO bov or bypass valve)