I have an S4 13B FC. My pulsation damper burst. can I replave my S4 fuelrail with an S5 fuel rail that has a built in damper?

 

yes you can, but be sure to use the proper fuel injectors. The S4 injectors are different from the S5's, so just use your injectors with the new fuel rail. In either case, I actually recommend that you dont do this--IMO you are better off sticking with the S4 setup. The S5's are prone to the same problems that the S4's are, and next time you would have to replace the whole PD/fuel rail. I got my last PD from Mazdatrix and have had no complaints. It may be a little more $$ now, but a new S5 one is even more.