I was looking to upgrade the exhaust this winter on mine. What are people using and any pros/cons?

Don't waste your money on aftermarket exhaust on a SBC marine motor unless you wind it north of 6000 rpm. You will see no gains with the exception of a lighter wallet.

Donzi ZX is probably big block. Maybe sbc if twin engine.
JRalston, you are best off doing a plan that does the engine and exhaust at the same time. Upgrading from OE exhaust is necessary if you improve the engine, but does nothing except look pretty if the engine stays as it was.
That said, many upgrades require better exhaust.
What is your power?

one slight advantage: You are beached on the sand bar and this cutie is bent over the side of your boat thinking "I want a ride in this!" And you are standing behind her thinking exactly the same thing... in reality the one upgrade to consider is aluminum oem exhausts. Between them and alum intakes you are taking a couple hundred pounds out of the stern. Unfortunately, the previously mentioned cutie will think "Stock exhausts? Loser!!"

twin 350 MPI's. was looking for exhaust this winter and prochargers next off season.

That is worth the money right there!!

So how much power per engine are you thinking of in the long run? And what cond are your existing exhaust in? Because this is something that can be found used with some patience...

LS3's and new manifolds to now fit the new engines...done.

Sell your existing mpi motors to all the cruisers looking to upgrade or replace.

Blowers or 454's...simple and quick. LS's will be best but will hit you for more money.

Odds are the boat is built with engines too close together to install big blocks.