If your aim is for 300 BHP then you'll need:
Chip.
Hybrid T28 Turbo.
Uprated fuel pump (I've gone for a Walbro pump but Bosh 023 will do as well).
Stainless exhaust.
-31 Actuator.
Performance panel filter.
+ uprated injectors of some sort.

Their maybe other parts as well but those are some of the main bits, its best to talk to a tuner that can supply you the chip as to what they recommend.