I can answer two thirds of your question. I have the 7.3kw Kohler in my 2002 and could never keep it running properly. FinAlly pulled it out of the boat, brought it to a Kohler dealer where all repairs were performed and then reinstalled. This was done, the in and out, while the boat was in the water. It really wasn't that hard, several lag bolts hold it down with the various fittings easy enough to access.
Mine rAn for awhile father that but kept getting water into the cylinder and the thing quickly became toast.
Now I'm going to pull it permanently. Anyone who wants it is welcome take it.
