exhaust shutters
 

I am reading merc service bulletin 2000-13 and see it recomends for 496/8.1 L engines:

For sterndrive packages using a through the prop exhaust system, do NOT use internal shutters, external flappers, or resonators.

These are the flapper things in the Y pipe to prevent water from rushing in when you back up. Any comments on whether they should be used on a 502 mag or not when running thru prop exhaust?

I noticed a piece of one when i pulled out this year in the water outlet at the base of the transom plate so I was gonna order them to replace in the spring but now I am wondering if I should just remove them.

My 502's have the shutters in both the tail pipes and the y-pipe. They are in there for a reason, so if yours had it originally, I would replace them.

They won't last. ( the ones in the Y pipe that is )

Mine lasted about one hour ( I run my exhaust a little hot )

Yeah thats the thing they never last more than 2 seasons if lucky and a lot of time barely 1 and now I see merc has an update in a service bulletin to not install them in 496's