I presume its a Yank bolt on turbo with ewg he means. (if so bare in mind it might not fit too well on a right hand drive)
What engine have you?
400whp is probably about 480ish crank hp, 550 injectors wont do that on our fuel, Standard Type R box wont do it either, nor will anything engine wise.
I would be mindfull that the yanks dont seem to worry about spool up or driveability when choosing a turbo and look for an end resut rr figure, ..
If you are still on a 2ltr, then you have no point in looking at the likes of a 3076,