Technical Fuel pressure regulator placement- before or after rail

[Blaster3500]

I am planning to add an adjustable fuel pressure regulator with a return setup to hopefully have more stable fuel pressures. I see PFS places the regulator under the car before the HPFP/Rail and other PR/Fuel it place it after the return rail. I know generally after the rail is preferred. On this platform is there any real world difference on placement? It would be much easier and cleaner to mount it under the car before the rail.

 

[The Convert]

I had mine after the rail. Makes more sense to me because you’re regulating the pressure from the tank TO the regulator and thereby making sure the PI injectors are seeing that pressure, whereas if you place it before the PI injectors you’re not taking into account any line loss or drop in pressure in the rail or between the injectors.

 

[Blaster3500]

I had mine after the rail. Makes more sense to me because you’re regulating the pressure from the tank TO the regulator and thereby making sure the PI injectors are seeing that pressure, whereas if you place it before the PI injectors you’re not taking into account any line loss or drop in pressure in the rail or between the injectors.

Probably the best idea. Did you notice more stable fuel pressure after the regulator?

 

[The Convert]

Probably the best idea. Did you notice more stable fuel pressure after the regulator?

I never fully hooked it up before tearing the car apart and parting out a lot of things.