Baileys DV causing no boost

i just installed a bailyes dv in my car and after driving it for 20 min everything is fine then me boost only hits at 3 psi and then 20 min later it is fine. I checked for loose hoses everything is perfect. i sent the dv back and replaced it with my stock one and it ran fine.I got another one in the mail thinking the last one was bad and it does the same think any help guys thanks

try installing it in reverse