money,
engine,
turbo, (and wastegate if not internal)
manifold,
more money
ecu ( if running low boost you could get away with a gze computer and map sensor but it can only take so much) (and you might want t boost controller if said ecu doesnt have one)
you will ned to do something with the compression to lower it, be it H/G or pistons depending on how reliable you want it and how much cash you have.
Bigger brakes of your choice (again all depends on $$$)
And depengine on your gearbox diff combo - more money when the time comes that they break with the extra torque
I have never built one, and that is SOME of the stuff you will most likley need, do a search, not only here but the world wide web, there is quite alot of info,
and to help us out:
How much power are you chasing/ what boost do you want to run through it
What is your budget