I've done the Motorcraft conversion. I don't have much experience with the Carter. Mine was pretty poor when I got my car, and lots of the vaccuum stuff was already missing. I had a lot of stalling, idle would wander, etc. To me, for the $350 or so it cost to change, the process was pretty simple. I've done about 4000 miles since then, either highway or off-road on dirt. Average MPG has been around 12, but I have large tires for an Eagle, 235/75-15's. I probably need to re-jet the carb, there might be a few MPG in there still.