This is not an exchange program. This is a rebuild service that you have to send your injectors in to be rebuilt and you get back the same injectors you sent in to be rebuilt. So you know the mileage and history of the injectors. If you are sending in AD or AE code injectors for a performance upgrade there will be an additional $150 charge for converting them to single shot injectors. Once we receive these injectors they get cleaned and inspected. Then we replace the plunger and barrel assembly, nozzle, nozzle lift spring, poppet spring, refinish all sealing surfaces and install all new seals and gaskets. After completion these are bench tested on our Hartridge HA-230 flow bench to ensure flow rates and functionality. These include a 12 month warranty. If your injectors cannot be rebuilt with this service we will contact you and give you and proceed from there. .