Electric Fuel Pump: PSI and IP timing

[TonyS.]

My 1993 6.2l has been running for about a year with an Airtex E8153 electric fuel pump whose specs are 10-14PSI, 35GPH. After initially installing it I had noticed the engine idled faster so the timing must have advanced from the higher pump pressure. Now that I'm in the process of fitting a Racor 645 before the pump and I have the fuel lines empty I'm wondering if I should replace the fuel pump with something lower PSI, like an Airtex E8012. It specs are 5-9PSI, 30GPH. I don't want to kill my IP but would it really be worth it going to the lower PSI pump? Also, might my fuel economy increase with the lower pressure or am I off my duff thinking that would effect it? Thanks.