You can adjust the fuel from the metering head by undoing the black box (fuel pressure unit on the side) remove the little grub screw and you will find an allen key adjust which you can increase the fuelling. I did this on my mates when he got a chip, but you need to get a tuner to do it. The only problem being is that it has its limits.

I have seen a thread on this site where you can put a line from the charge carrier to the fuel valve on the return fuel line from the metering head and supposidly this increases fuel pressure also.

Only problem I can find is that no-one will tell me officially!!! We need Stu @ MSD or another top tuner on this site to give us some proper info!!!