Maybe not completely relevant but I can describe what my fuel pressure data graph indicates on a Super Stock drag car launch where the diaphragm/pintel style regulator is mounted before the carbs (both physically and hydraulically). Sitting on the starting line, engine WOT but rev limited to 6K, the recorded fuel pressure is exactly 5.5psi (reflects static setting without engine running) and the pressure graph is nearly linear. However, the instant I drop the clutch the pressure plot indicates a high frequency oscillation (saw-tooth graph) between 8 and 4psi. As initial forces of gravity diminish from the launch the pressure oscillation-frequency drops continually with the plot indicating a near linear characteristic by around the ⅛ mile (half track) through the end of the run. There are a ton of forces and counter-forces interplaying here but, basically, what the plot indicates is the the limits of the regulator's ability to control the dynamic fuel pressure under this specific set of conditions. There is certainly an optimal regulator discharge orifice size (a compromise) that permits an acceptable pressure control range combined with acceptable volume delivery but mechanically, as it does it's job it introduces these wild pressure oscillations. Apparently, we can make sufficient modifications the the carb delivery system to make it all work. I'm definitely not a FI person but my best guess is that placing the regulator post-throttle body would smooth the observed saw-tooth oscillations effects on the throttle body.