Got a 1999 4.6L Triton with supposed 195 HP (stock) and 355 gears. Wife has 2005 5.4L Triton with supposed 235? HP (stock) and 376? gears. Her Expedition is supposed to weigh more than my F-150. Hers spanks mine like a rabbit to a turtle...what gives? I know they've made changes to their engines every year, but exactly what? I'm coming up on 100000 mi, but it runs just like the day I bought it. I know that eventually, it will need to be worked on, so I'd like to know what modifications (updates) I might be able to do while I'm in there. By the way, she gets much better gas mileage than I do!