Michael said: "What I am experiencing is loss of power. When I increase the throttle the rpms increase as usual, but the boat does not accelerate as it should" If the RPMs increase but the boat speed does not then it is an indication that your tranmission is slipping. That wouldn't have anything to do with your exhaust. Perhaps when you increase the throttle the exhaust simply gets louder and you are thinking the RPMs increased? Watch the tach next time and verify that the RPMs do increase. Aside from that, it sounds like your muffler has been fried. As Trace said, it sounds like you ran without cooling water a few times. Don't do that! The first indication that your impeller has gone is that the exhaust will get louder. This is because the water flow through the exhaust is very important. When the flow of water stops the exhaust gets louder due to the gases not getting cooled and the baffling of the water is removed. If you run for any distance without cooling water the exhaust system will overheat. On the engine the exhaust manifolds are cast iron which can take the heat. At the "riser" the exhaust and cooling water are mixed and everything downstream of that is rubber or fiberglass which can NOT take the heat. I have seen boats sink because their impeller fried, lost cooling water and then the 4" rubber exhaust hose melted, opening a 4" hole in the back of the boat. If you suddenly hear your exhaust get loud, STOP! Shut the engine down ASAP. The exhaust system can fry much faster than the engine will overheat. And when you say you "go through an impeller every couple of years", does that mean you replace them on a preventative basis, or they fail that often? If they fail that often then something is wrong. Are you running the engine while the boat is on the trailer? You don't want to do that either. Rod
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