Re: Closed cooling for Mercruiser 5.0 2013 with cats
If you are going to be in salt. . . go for the kit, particularly if it is a "FULL" system kit. (and if a FULL system kit is more $$$, it may be worht the extra). The engine will last 20 years or so with salt water going through it, but if/when you go to sell in 5 years or so, a prospective buyer won't really care, and will discredit the boat.
If you have run the boat on a closed cooling system, then the salt water issue/concern would be avoided.