As for requiring a FASS pump... You don't need a FASS pump till 450-500 HP!smokeyourdiesel said:5 years or 100000 miles which you are past the five years. if u do not tap your pump then the comp just acts as a ez. to get the full 120 hp you must tap your pump. just make sure that you have some kind of a fuel pressure gauge and a pusher pump or fass. when i had just the comp on my old truck i could it suck the fuel pressure all the way down to 4lbs. i did that once or twice then i got pusher after that bigger injectors and then i had to get a fass. so if you need a fuel pump go big an be done. bigger is always better.