My LS1 that is going into my '71 is from a 2000 Camaro that had a returnless fuel system. My '71 will get a return system with the Spectra tank and Walbro pump. I think the factory returnless system controls the fuel pump with the ECU, and slows it down at idle. Since the fuel pump slows down and speeds up based on load, does the fuel pressure go up and down throughout the map? Or does the fuel pressure regulator keep the pressure at a constant 60psi despite the pump slowing down at idle. I'm concerned that once I convert my LS1 to a return style, and set my FPR at 60psi, that I may be flooding the cylinders with fuel at idle since it may not be used to 60psi at idle. I hope that wasn't too confusing, not sure I described it well.