I dont know what the big deal is over this 5.0 engine its just a couple cubes more with 2 more headache cams(plus variable timming). How long have 4 valve heads been out now on the mustang since 96. Equal the cubic inches with head flow and it will run the same if not better than the 5.0. I know some of you will hammer me on this but the 4.6 still sounds better no matter what.
i think the heads are where the big diff is going to be, they are hella nice heads from the factory