Sounds like the HKS SSQ.
Some people have had good results with the HKS valve due to the dual piston valve design, Personally I don't know, but on my car setting the Greddy valve to blow off to atmosphere gives an almost instant limp mode.
It might work. Turbosmart are a good company they make quality products. I have a manual boost controller by them it shows quality manufacturing.
Note that if someone says they have used it and it works fine it does not mean it will be fine on your car. Different engine codes and years behave differently, like I said, on my car a blow off valve gives instant limp mode, but some people have no problems.
hope I've helped.