Pretty sure the boffins at Subaru would say yes.
Why do you need a Blow-off Valve (
BOV)?
To eliminate compressor surge when changing gears. Excessive backpressure is created when the throttle is closed during gear changes or deceleration, causing turbo cavitation. This is detrimental to the life of your turbocharger; however fitting a
BOV will substantially improve this problem.
By installing a
BOV you will significantly reduce turbo spool up time. You will notice a substantial improvement in response from your turbo between gearshifts. Boost will come on earlier giving an increase in torque at lower RPM.
I'm no expert though... (no sarcasm intended as I really am not an expert.)