The tab doesnt matter much. The water comes in at the rear cylinder, you want to limit flow to the head of the rear cylinder which pushes cold water to the front cylinder then through the gasket. If you put the large holes at the rear the water will flow up through the gasket and out the head at the rear cylinder, leaving the front starved for proper cold water. water always flows the path of least resistance, and larger holes mean less resistance and more flow.