I have a 1990 454 Magnum Gen IV motor. It had the old six hose thermostat housing which had the balls and fed the risers and the manifolds. This spring I upgraded exhaust to EMI's and added the thermostat housing which is found on the Gen VI motors with the four hoses. Just two that go to manifolds. Has anyone ever experienced water flow problems when adding this newer thermostat housing to a older motor and what did you do to fix the problem?