I purchased a new set of Brodix bb3 cnc heads for my spare long block build and I'm going to swap out the exhaust valves for fererra super alloy valves, I talked to brodix and they said that the standard intake valves that came in the heads will be fine for marine use, does anybody disagree with that? I have no problem spending the money and buying better intake valves but if its not going to make a difference then whats the point

They should be fine.

Find out what material/series valve is in the head.If the series is a ferrea 5000 or equivalent,then they need to go.If there 6000 series or better,then you'd be fine.
I take it these heads will be on the whipple motors?Then get good valves.

Brodix valves will be fine. I have run several sets of the brodix valves on blower engines and never had a single problem.

Only had 35 hrs on them in a blown deal, but the Brodix valves in my 2x heads were in fine condition; both intake and exhaust were Brodix installed parts. So, I would not be concerned with their intakes. I am re-using their intakes and replacing the exhausts with superalloy just to make myself feel better.

If you have an open cooling system make sure the guide clearances are right.

Exhaust Valves are your concern. You shouldn't have problems with the intakes. They pretty much stay closed, happily transferring combustion heat into the valve seats, while the "inferno" is happening.

High rpm nitrous or blower motors that are susceptible to valve float definitely need fireproof valves.