OP - start by reading all the big turbo threads. You will learn a hell of alot from them, parts, compatibility, results, problems, preventative measures, tech stuff, and the shear amount of work involved.
Ive only recently started my build, and let me tell you its a lot more work than you first think!
Takes planning, takes money, takes knowledge to get you where you wana be in the end.
Once you've read up on things and got the ball rolling with what you're going with hardware wise, you can start asking informed questions that we can answer/advise.
But right now 'what turbo will give me 400hp?' is far too ambiguous. Well, its simple to suggest a load of turbos, but thats only a fraction of what you need to know.