Hi all. I am planning on tearing into my engine compartment of my 2004 Chaparral Signature 270 with twin Merc 4.3 mpi with Beavo 3s. Impeller went out on Starboard engine about a month ago but the temp alarm shut it down before it got too hot. I pulled the boat out of its slip to take it for service and had new impellers, and both engines fully serviced. I put it back in the water and idled our past the no wake and once it got it up on plane it started feeling a little sluggish but no alarms. I backed it off an tried to take off again to no better outcome. Popped engine hatch and the belt was shredded about 3/4 through and slapping around on everything. I called the boat yard that serviced it and they came down and put a new one on and blamed it on the belts age, (bull crap). Too much coencidence being it was just removed and put back on a few hours ago. I took it back out the next day and ran it about 20 miles or so and on the way home I got another lag in power followed by a huge steam cloud coming from hatch. It blew a hose coming from the water pump up to the top of engine. Again I call the boat yard and they blame the hose damage on the belt beating it up when it shredded. We replaced that hose and the next trip out it blew the elbow off the exhaust boot. Replaced that and now it trying to build pressure and blow other hoses. Friend thinks it’s head gasket or heads. I build houses and have no mechanical knowledge but am going to start pulling parts in the slip this weekend. And help or diagnosis suggestions would be much appreciated. I’m hoping for simple but prepared for terrible!