I'd like to see some pictures of the engines and outdrives. The things you are describing are replaced on 15-20yr boats and usually never, not on 5yr old boats. Couplers, engine mounts, exhaust flappers, they don't just go bad or wear out - something happens. Sorry to hear about your troubles, but there has got to be more to this.
______________________________ 1999 SeaRay 185 Bowrider - Current
2000 SeaRay 290 SunDancer - Previous
1979 Correct Craft Ski-Tique - Previous
1948 Chris Craft Custom Runabout - Oh man to have that one back!