the FPD does just that. it dampers the fuel pulse to smooth out the actual line pressure the injectors see. put you hand on a fuel line and rev the car you can feel the pulses even when everything is "stock" and correct. you need it unless you have a FPR that will act as one.

alot of Forum Engineers will say it is usless. i have yet to see one that just went and was not an ignored fuel smell from the owner. is this on an fd?