any other ideas...
Putting a -8 fitting on a -6, [3/8"] line, will result in flow the same as what you would get w/ -6 all the way to the engine.
If you measure the ID of the OEM "3/8" line, it's not 3/8, due to the o'ring seats that are made onto the ends.
But then, a famous TR tuner once said that stock lines were good to 1000HP......