IT should be fine.. I have known people with webers to run without Regulators for years and not throw the weber needles off. Its just to be safer than sorry, could be costly doing damage to the webers. Just dont Rev to high to much until you get the regulator. because the PSI off the Stock fuel pump works off the cam lobe more RPM more fuel pressure. I have heard the stock mech fuel pumps are good for 13psi.