if your engine compression have around 9.0:1 ratio then u don't need to change piston in this case.
if not, u gotta source some piston which will give u lower compression to replace your current one.
if your engine is mitsu model, the standard conrod can stand up to 0.8 bar boast.
Other models i dunno lar.
u need a new set of injectors around 275cc one should be sufficient.
u must have a fuel pressure regulator as well.
other stuff like td-04 turbine, custom turbo manifold, custom dump pipe, all the hoses and fittings, blow off valve, boast meter, intercooler u must have.
but it is highly recommended u buy a piggy back computer like Greedy or Apexi one to fine tune your fuel. its bad not to provide enuff fuel when your boast comes in.
i think that's about it.