Yeah its likely opening when it senses 1-2 psi right now, which would be fine with a turbo (because it won't stay at that low boost very long as it spools relative to engine load) but with a supercharger not so much so (because as long as your engine is at that rpm range that's the boost you will make regardless of load). You need it to open with vacuum. Cheap doesn't mean bad though. I have had luck with plenty of white box parts....the only difference is there is no support for them and they are very generic so they force you to learn how to tune it yourself instead of it being right on the money out of the box. The cheap parts can be good to learn on and experiment with, no sense in spending $200+ on a bov just to find out wether or not it will benefit you.