Also has garbage tuning ability. As they said, what is your budget and/or level of mechanical ability (and please don't say something to the effect of oh I've swapped such and such engine in old cars; it's not the same)? Because you basically want turn your truck into a mutant no one will most likely want nor will you likely be able to trade in (once they run the VIN and figure it our something ain't quite right lol) and not necessarily be reliable. Upside is the 4.7 & 5.7 or 6.1 use similar engine management. I wouldn't even bother counting the 6.4/392 in this discussion because that is a VVT/active intake/possibly MDS next gen engine that you don't really have a snowball's chance in hell making work in an 03 Ram unless you have unlimited dollars for the people who would have to try and make the computer modules play nice with each other. Easy part for the 5.7/6.1 is that it will drop in and bolt to your transmission (aaaaaaand that's where the easy part ends). The 4.7 PCM isn't designed to fire the coil setup on the hemi (especially since there are two different styles). The hemi has electronic throttle body (which your truck is not wired for because 4.7 is cable). Exhaust will be different, requiring changes (or new), especially with 6.1 heads as the exhaust ports are shaped different. If you stay with a truck version then your accessories will work, however if you decide you want to try and use a car intake manifold you're screwed because of TB location and accessory drive placement; 6.1 heads also have different/bigger intake ports as well. It branches from there, especially since you actually have a goal of 400-500hp (you weren't specific with crank hp or wheel hp). You didn't specify whether you had a manual or auto, but regardless the 4.7 manual will most likely not stand up to that power level and if auto that 545RFE will live for awhile but I'm betting you like to romp on it; it won't last all that long at that power level.
