Ford could have made 500+hp naturally aspirated on the GT500. And the car would weigh 200-300 lbs less. Audi uses direct injection and is making 419 hp out of a 4.2L (254 cid) motor in their RS 4 sedan. That's 1.65 hp per cubic inch based on a quick running of the numbers. On a 5.4 (329 cid) Ford that's 544 hp. Subtract 44 hp to run at lower revs then the Audi and Porsches and you still meet your 500hp goal. Porsche on their GT3 makes 415 hp out of 3.6L (220 cid) and it didn't mention direct injection, and 605 hp out of their 5.7 L V10 in the Carerra GT. Toss the supercharger on the 5.4 and that should have paid for an aluminum block and an engine design that is current. They've been designing, building testing 4 cammers for well over 10 years!