Fuel pressure regulator, correctly set for the given boost requirements. Some, such as myself, run upgraded fuel pumps, but they're not really that necessary and are more of a precaution. Once the fueling is sorted, you will need a Fuel Cut Defender to remove the stock fuel cut, but
only when the other supporting mods are in place.
As CMR rightly said, you will need to get yourself a new manifold, the stock one has a restriction in runner #3 that will make your day a shit one if ignored. I would also recomend sourcing decent plugs and leads. Magnacor 8mm (blue) and 8.5mm (red) plus HKS Iridium plugs (Heat range 7) seem to be the items of choice.
You will also need to upgrade the brakes, no good being able to go faster if you can't stop quicker.