is 4.5 psi too low for a sbc with an edelbrock carb? i have a mr gasket pressure regulator set at 5.5 which is recommended for the carb but i only get 4.5 on the gauge. if i take the regulator off i get about 7.5 to 9 which is too much.

In my opinion, 4.5 psi is ok. More pressure will not make more horsepower, it will only lead to over-powering the needle and seat and lead to tuning problems due to an over-rich condition.

The key to a good carburetor fuel system isn't pressure, it's volume. Make sure you have lines of sufficient diameter. 3/8" daily driver. 1/2" street/strip.