What’s not to love about the thundering GT500? If you’re lucky enough to have an ’11 version as shown here, not much! But previous iron-blocked GT500 engines weigh 102 pounds more than the all-aluminum ’11 version, which doesn’t help performance one whit. That, and the tall 5.4 engine is a tight fit in any pre-S197 Mustang, which makes headers a headache. In the end, the blown 5.4 is a difficult, expensive engine to swap.