Since the elbow isn't the biggest restriction from the factory replacing it does little to nothing other than bling factor. The factory elbow is thick enough to drill and tap for ports too. That's my advise if you're on a budget.
2006 True Blue/Silver F250 Crew cab
Just the normal bolt ons...
butterfly is to increase egr flow. Thats why the early trucks had them (though not actually functioning on some models). Ford then switched to the scoop in the up pipe, cheaper way of accomplishing the same thing.
if you buy an aftermarket elbo that does not accept the o ring, they generally blow the paper gasket out and cause oil to leak all over the place.
If you have the butterfly remove the two screws holding the plate in place and remove it if your that concerned. (i'd remove the throttle body before doing so incase you drop a screw so it does not go down the intake) the shaft that's left behind won't do #### to limit restriction.