Pm sent.
Generally unless the injectors are racing customizable units or many diesels injectors cannot be rebuilt or remanufactured.
some plastic housings can be reused with brand new internals but not the metal body style you have.
They are sealed when they are built and trying to get into the pintel, disc or coil will destroy the unit.
They can be cleaned, tested, new filters, pintel caps and o rings thats it.
The problem with many ebay $100 sets is these guys buy cores by the barrel. they have no idea where the units came from or how many miles are on them.
There may be 50 of the same type in the barrel. they dig sets out, clean them up and flog them.
There is no guarantee they were cleaned properly or the flow measurement they take are accurate.
Many of these guys just static flow them and find 8 (example) that flow the same and there they go.
Auto flow which closer duplicates the actual running of the engine is much more accurate but it also has a much higher discard rate. Too much trouble for many.
Maintaining the equipment is also important in obtaining accurate readings, old fluid that may have cleaning solution in it is inaccurate.
There is a lot to know and a lot of diligence involved to do them right.
