I have a 2002 F150 (4.2) and I want to either put a 4.6 or 5.4 into it. I need to know which would be better. I want to produce at least 400hp. Should I buy a wrecked, used, or turn-key? What will line up and what won't? Yes a lot of questions but I'm new to this and I'm really interested in putting a new motor in my truck. I love the body style and do not want any others. Anything can help...