It take me less than an hour to replaced my 615cc injectors but I kept the original fuel rail for now. Make sure you use motor oil and lube the o rings. And do not force the injectors in with the injector cap. Use your hands to push it down till you feel it pop in. FYI if you pinch the o ring the fuel will leak into the engine and it will not start unless you step on the gas pedal. That's if you let it sit overnight. Just had that problem with my Z one of the o ring was pinch and had a cut. Good luck let me know if I can help
