The wrx is my first turbo vehicle. I've done some minor mods already:

HKS catback (plan on adding an HKS down pipe soon)
Kartboy shift stuffs
and I have an AEM cold air intake coming soon

I my current goal is a bigger turbo. What do I need to prepair for a bigger turbo?

I want to do this right so I think getting everything else ready to maximize the performance of the new turbo is my best plan of action.

I imaging a piggy back or new ECU, (which one is good)
EVC, EFC (I've heard Apexi makes the best)
What about engine internals?
Intercooler?, BOV?

Any help would be appreciated.