Good point , Brownie. I use a circ. pump simple to avoid hot spots. The way I see it if Merc and others could make $10 more per engine by eliminating the circ. pump , don't you think they would? Of course on the flip side of the coin , Merc also sells REPLACEMENT parts too. This could be a money maker for them

I purchased and installed a cross-over on my `98 7.4 MPI. I have the single serpentine belt. I got the type with the idler pulley made onto it, for use with the serp belt.
The results:
I saw nothing.........
The main reason I went with the crossover was partially cosmetics and partially to rid myself of my leaking circulating pump. $500 clams later, I need not worry about circ pump failure.
It sure is purty, but save the $500 for something more revelent......

not to forget the new kit that gets rid of your circ. pump has a idler, well it also has a bearing in it that can still go bad, me I just change my circ. pumps every three years are so and you will not have any problems, impellor drag in a cicr. pump is costing you maybe 7 to 12 hp. . leave it along unless you have big horsepower with a pressure are a overheating problem

If a person wanted to go with a crossover on a single application, would he need to get a pressure gauge and a different t-stat housing?

Your t-stat housing is connected to your water pump, and also has the main water inlet. Since both of these change with use a crossover, the answer is yes.

Always use a pressure gauge when changing from stock design.

Hey I have a 1998 502mpi fairly stock purchased Hardin marine Crossover kit little concerned about installing it is it worth it or not?

have run 3 different crossovers, no issues at all, if you run without a bypass and themostat will run very cold usually...my procharger setup requires their crossover...