I would go with remanufactured (they all are, even ford) from pensicola diesel. I just put in a set of their 40 hp/110 ft lb upgraded injectors. The problem with ford injectors is that they only carry a 12 month/12K mile warranty whereas the Pensicola injectors are 12 month/ unlimited mileage. The guys at Pensicola are awesome to work with as well.
My fuel mileage increased by 6 mpg pulling no load on the expressway at 60 mph. I also see an increase of 3-5 mpg pulling a 25K lb car hauler. 7 mpg increase pulling that 25K trailer through the smokey mountains vs. stock. ALOT less downshifting and very good power.... Win, Win..... $1450 bucks for the set.....