Pulled out my boat the other day - ran it for five minutes on the hose and got really surprised. Port side exhaust manifold, riser and exhaust pipe was just warm or even rather cool as it should be. But on the starboard side, manifold and riser was uniformly warm/cool but the exhaust pipe was so hot it got me swearing when I touched it. So how's that possible? I would imagine if there is lack of waterflow or obstruction or something then also manifold and riser would overheat? But only the exhaust pipe? Any ideas?