The 4.6 is considerably heavier than even an all iron 5.0. I've got the fiqures at home, but its very heavy for the size. Also the rods are a lot longer (RL/S ratio in the neighborhood of 2.20 I think). anyway, not only is it heavier, but a lot wider too. Yes, if you want a technologically "newer" motor, the 4.6 is great, but for the real world, the 5.0 is too practical. It's a lot lighter, much smaller, and the R&D is at the peak of the curve for aftermarket parts. And mid to high 300's in the hp figures are not too hard to come by. Even the 351W I think is lighter than the 4.6, and is still smaller to boot.