Agree. The pressure on the Carter 6270 will get high enough (6.9 to 8.1 psi) to require a regulator. I was running a Carter 6270 (opened up to 3/8") on my 408 equipped with a Pro Systems Pro Series 4150 Holley. I bought the pump from FBO and Don assured me it did not need a regulator. The pump was always on the ragged edge of overfilling the fuel bowls and causing the carb to run rich and occassionally flood. I did not want to run a regulator so I switched to the Edelbrock Performer RPM Street Fuel Pump 1720.