Someone made a comment recently(in the last year, if I remember correctly) that they wanted the fuel pressure set at or under 5.5 to 6.5 lbs to reduce the possibility of aerating the fuel from the tank to the carbs I had my fuel pressure set at the regulator with the engine running at a idle at 9.5 lbs, I reduced it to 6.5 lbs and didn't see any noticeable change at the track or on the street My car is not real fast (10:34 best ET in the 1/4 mile) so my results may not carry any weight, your results may vary I did find out later using a O2 wide ban that the car didn't have a good enough fuel system to allow me to fatten up the carbs big enough to slow the car down until I switch pumps from a Magnafuel 275 to a Magnafuel 300 pump,whch did slow the car down with no other changes made to the car except the pump switch My message is if you can slow the car down in 1/4 MPH by fattening the mixture up enough until it slows down your fuel delivery system is probally okay, no matter what the fuel pressure gauges reads during the run, if you can't fatten it up enough to slow the cars MPH down you probally have a fuel delivery problem. I did not say fuel pressure problem Air in the line can compress showing pressure when it is not all fuel in the line flowing