Logically, in theory the larger end should be on the side with the water flowing out and the smaller end to the other side. This in turn has no flow disruption, no direct leaks, and for future longevity if water had debri or small twigs and leaves it wouldn't get caught or snagged on inner lip of repaired pipe causing piping to block which in some cases can happen! Good simple repair video though.The presenters expertise shines through, making the video a standout in plumbing tutorials.