i highly doubt the t25g (std turbo) can flow more than the stock fuel pump can cope with......it's quite a small turbo. so i imagine you'll notice no difference even with the standard fuel pump (if you notice it improve, then chances are you were damaging your engine before).
however, the fuel pump is quite old by now, they can fail, and when they do sometimes they cause a slight lean out and if you don't notice the pinging you could be saying bye-bye to your rings quite quickly.
i'm getting a new fuel pump quite shortly, will probably go a bosch 984 for no particular reason. i've never changed a fuel pump before so no idea at all which will be easier to fit, but i'd say the 040 is quite a big pump.