6paks came from the factory with a 8-9lb pump, BUT they had a .060" return orifice in the vapor separator that helped control fuel pressure. i just went thru a high pressure fuel thing with one of my street cars. anything over 7lbs can cause problems and seems that 6-6.5lbs is a sweet spot. i use the 6903 pumps and do some mods to them but run a return of some sort. i also think large needle and seats can be a problem with higher pressures. the floats just can't control the flow, especially at WOT. i don't know your power level but stock 6pak fuel lines with the separator can handle 450hp. if you want to keep the braided hose then try to rig up a return line. i prefer hard lines myself, but braided may be better for someone pulling a lot of maintenance.
The vapor separate comment is misleading, because Mopar fuel pressure spec was measured at inlet to carb and included the separator as part of the system. Hemi pump was 7 to 8.5psi, the 440 HP was 6 to 7.5psi. Mechanical pumps are constant volume pumps. If the diaphram or the airdome age and harden the pressure at outlet rise because less give/expansion of the rubber to buffer the pressure pulse.
