You need to decide a game plan really.
Where do you want to take it, i.e. what power do you want to end up with....
If you want big power, i..e 215+bhp then start with an aftermarket ECU, then you can have a choice of cams or ITB's or Supercharger or Turbo (you will get nice gains from just the aftermarket management)
If, your looking at simpler mods without taking it too far then:
matched inlets
Sports Cat
Exhaust
Cams + Remap
these will give you nice gains....
it all depends what you want from the car and what the budget is.... if you have a long term plan then its easier to steer the direction on mods.
If you need some help drop us a line
Andy