it should came with another spring that is stiffer then the one already inside the boost controller. that what happen to me when i installed mine and it only boost to around 12psi, even with the boost controller turn all the way. Then i switch the spring and everything is fine. If you going to switch the spring on the black one to the red one, make sure u turn the boost controller all the way down first.

 

im having the same damn problem

 

i actually things to do tonight, so ill test the springs tomorrow. hopefully everything works fine, if not i will have it shipped back out tomorrow.