if ur thinking about a 5.4, u need deep pockets like trubble. u need a custom intake manifold for a 5.4 dohc that goes for $3k. if u go for a 5.4 2v, its not that much better than a 4.6 2v, might as well keep ur 4.6 2v. and either way 400hp N/A????? reality check , it will cost a lot of money and not be that streetable. KISS, keep it simple stupid, not trying to offend u, keep ur 4.6 2v , buy a forged rotating assembly and either supercharge it or nitrous it. believe me ull have enough power after.if u want something unique, drop a 4.6 4v out of a mach 1/ or if u can afford 03 cobra. either way good luck :thumb: