honestly, I'm lost here. you're talking a gt30 turbo, so let's say (being generous) it can make 320kw@wheels... 850cc injectors are MASSIVE overkill, as is pretty much any other mod you can think of. a 1uz will do 320rwkw without even blinking - like 1jz.747 said, until that turbo gets a hell of a lot bigger and multiplies, you don't need to worry about any other mods.

everything else about that car (exhaust, injectors, bigger fuel line, etc) suggests it's made for over 400rwkw... so get yourself a/many turbo(s) to support that