8 gpm is about 4 feet/sec of fluid velocity in a #16 line which should be fine for a suction line. If I need to make any changes to the inlet hose I might upgrade to a #20 line since that would reduce the suction resistance and the flow velocity even more. My inlet line is only about 3 feet long so I don't think there is any issue with the #16 line but bigger is better on the inlet side.

Did you guys ever run any oil pump flow tests in the dyno room?