That's what an FMU does. You need to find out at what ratio it adds fuel pressure in relation to boost pressure. As I said, if it's 12:1, or 12lbs of fuel pressure per pound of boost, then you need an inline pump. You're right, the GReddy kit should work fine without any add-ons with just the box, but if your box has gone bad(which some have been known to do), then you need to either get a new one, or switch to a different form of fuel management. If your Holley FMU is adjustable, you need to get it up around 12:1, and run an inline pump to supply the pressure it needs. Or, you can switch to larger injectors. Anyway, I don;t need to tell you that a lean condition on a turbo engine is a disaster waiting to happen, so I would try not to boost until you get your fuel issues resolved.