Ok so no idea if this is right but my car at the moment only boosts to 5 psi. I'm sure from what I have seen on here thats wrong! I have fitted a MBC and it does as it should and I can get upto 10/15 psi. How ever when I do this as soon as the boost reaches anythink over 8 it goes limp and feels like some giant is pulling the car back. Anyone got any ideas?? As I said before I have no idea what it is but it's almost like the car is cutting the fuel. All help will be greatly received.