for 400hp I'm guessing somwhere along the lines of 15psi, and fwiw, I believe you will definately need forged rods for that power level.
If you truly are gonna run in the neighborhood of 15-20 psi I think that turbo is ok, but anyhting less would demand a smaller turbo, or you will end up with a power curve like the last turbo 'tour that was posted.
Good luck, and let me know if I can lend a hand in any way.
