1997 Carver 325 exhaust collector

[carver#325]

Just wondering if anyone else has removed the backflow valves in the exhaust collectors? I cannot see the need for them as they are well above the outlets under the platform and after the muffler if looking from backflow direction. There are also rubber flappers on the outlets.
I'm assuming that the exhaust is still factory installed at around 1100 hrs.
The pivot bushings in the valves were completely worn out and rattling. There's two valves in the collectors, one for each bank.
I have removed the valves in the starboard side collector in prep for next years boating season and want to be sure i'm not missing something here.
Thanks.

[Cooler]

I have had similar thoughts on those backflow valves, but keep coming back to the same conclusion,...if they did not have a purpose, they wouldn't be there. I did replace one due to a crack in the fiberglass exhaust connector, but replaced it with a stainless steel with valve. That can be obtained at Marysville Marine. I was on a friends boat, Sea Ray, when he aqua-locked his engine due to water coming back thru the exhaust. Process to get water pushed out of pistons was a PITA. Good luck. Maybe Viper will chime in. er