If you really need all that hp why not buy a GT500 or a Vette? You get 650hp right out of the box. You can pick up a used 2013 Shelby for the price of a $45,000 NISMO plus the $10K FI kit. And the Shelby is designed to handle all that HP. You wouldn't be pushing the engine to near or beyond it's design limits since it's already designed from the ground up to run built-in FI.
2013 Ford Shelby GT500 For Sale - CarGurus