Engines are 502 mag efi, closed cooling system, stock. I will be adding headers and would like to hear what ones would be the best bang for the buck also should I make them part of the closed cooling system for better life? Would it make a differance?

Any comments?

There are lots of diagrams available on closed cooling systems. I don't think the exhaust can ever be part of the "closed" system. Not near enough cooling capacity available to cool headers.

I'd say your type of boat would factor in to new exhaust type. If you want absolute trouble free exhaust, you may have better luck with aluminum manifolds and stainless risers. If you have a go-fast, maybe tube headers like CMI, Stellings, etc. Personally I like the Stainless Marine manifolds and risers.

You won't gain too much performance with either but reliability usually goes up with aftermarket aluminum manifold/stainless riser combo, especially as compared to older style Merc. Depending on engine room size, some style tubes may not fit too well if limited in space.

Of course, just my opinion.

Going in a F402sr1 Formula, I have a set of Lightning Headers mild steel now but was thinking of going stainless for less trouble down the line. Love the sound of headers sooooo they stay! Room is not any issue as there is lots there to work with. I will post pictures as the job get going.

Headers canot be part od a closed cooling system even if you run them dry. Your best bet is to run a good stainless system. Lightning makes a great set of headers and can't be beat on price. Revolution Marine make another much more affordable exhaust system of headers are not an option for you.

As far as extending the life of your exhaust you should allways flush out after running in salt. I make it a habbit to drain the exhaust after I run, ALLWAYS.