inspyral: If you refer to my first post, you'll see that I'm running a piggy-back that controls fuel and timing relative to boost, a "missing link" (aka, a check valve assembly), and bigger injectors (I do run the 310's that I recommended). What you are saying about FMU's and stock injectors is true, and that adding ANY type of additional or replacement pump won't do that much to fix that situation (Yes, DRAG and REVhard can squeeze out maybe a couple of extra PSI intake, but they are also designed as intercooled systems along with the in-line pump). I'm kinda a d!ck about the whole FMU thing, as its only a band-aid for better forms of fuel tuning.

As far as the Greddy box goes, the only function I know that it performs is that its supposed to block an out-of-spec signal from the MAP sensor. That will give you a CEL if you get above around 3 PSI or so. Some newer piggy-back systems can use the stock MAP sensor up to around 1 BAR, but need a different MAP for higher boost. The only real fuel tuning I know of comes from the FMU itself, and that its rate is tuned to the volumetric amount of additional fuel that you can get from the injectors for a given increase in fuel pressure. The amount of fuel-flow increase, though, decreases rapidly as the momentary fuel pressure increases. I don't know of any function that the box performs that adjusts duty cycle itself - I don't think that it really does anything else.

jfd: If you haven't noticed, I'm down on the whole fuel regulator idea (recall my "Death" post). You shouldn't need to adjust your static fuel pressure unless you have increased your engine's nominal air demand or replaced it with a bigger engine (see my last post). Also, I'm not a big fan of the in-line pump idea: its more tubing, wiring, and work than running a high-flow/quality in-tank pump (insert KISS principle "here") along with competent fuel management (ECU or piggy-back). That's what I've done and been running that way for several years without any problems caused by this setup.