are you purging to atmosphere or recycling the BOV waste back to the hose between the AFM and the turbo?

a lot of the DSM valves like the one you have blow off light and the popular fix is o stick it in a vice and crush the top down to raise the blow pressure.

I personally have had good luck with a stock toyota BOV from a supra 7mgte, it was meant for a car running about 11 psi and it pops right on cue when I let up on the throttle.

the Bosch unit in my wife's Audi a3 is nice, too. pops in an accurate and timely fashion and makes a nice little "whoosh!" noise. those you can get at any parts store for under $25.