I am not sure I would call it a Low Performance pump. More like Undesirable pump. The E and F pump are insert pump and said to have a proposing problem in some hulls and because of the inlet water angles. have a 1978 Baja TC day cruiser with a 502 and an F pump in it. It will run 65 mph all day in it with no problems. The E and F pump where not favored because the difficulty to add a shoe to but from what I understand there is a company building a shoe/ ride plate set up for these pumps.