Just joined the forum and figured there would be some experts on here that could offer some advice. I just bought a used boat with the 420 hp 8.1 Volvo Penta in it. It has the Corsa Captains call in it and it was leaking water in to the boat where the flap actuator goes thru. We pulled the exhaust to replace the o rings and discovered these plates welded in to the ends of the exhaust where it goes out the side. I thought it was very quiet when I activate the thru hull compared to some of the hot rod boats I hear on the lake and am wondering if this is why? Just wondering if this will quiet the exhaust down a lot and if I should cut these out. They seem very restrictive but maybe they’re all like that? Not sure. The exhaust dumps out the side and has a nice rumble but not as loud as I thought it would be. Just wondering if this was an option on these or are they all like that. Any issues with cutting these out or will it make any difference? Ive never had a boat with captains call before. Look forward to any thoughts any of you might have. Thanks guys.

Can you get a skinny Sawzall blade in there? That will cut it if you can.

I'm sure I could get them out fairly easy. They just have little spot welds but I'm wondering if there is a reason for them being there or if they are functional or just there to quiet the exhaust down. They look like they would be fairly restrictive but not sure.

Yes those will reduce noise a noticeable amount. I don't think they would make a real world difference in performance on that engine, but I could be mistaken.

That was the other thing I noticed on these. The diverter is after the down tube that sends the exhaust through the prop so basically it's always sending exhaust down through the water and then through the sides as well if you hit the switch. I wonder if this system was designed to just give you a little more sound but not a full performance version where 100% of the sound is either through the prop or through the hull by hitting the switch?

Had similar on boat years ago. Knew a lot of folks that cut them out. I would replace with open tips myself if that was what I was after. Mine were a little different, looked even more difficult to empty out. Made me think replacing was the way to go.

I remember Bob Teague writing in the Power Boat magazine (years ago haha) tech Q & A that you could push around 300 HP through the prop before it became a restriction. I am pretty sure those silencers are good for the other 120 HP at least, so I think the only thing you are going to gain by removing them is more noise considering you are at 420 HP.. Now, if you were running those silencers without going thru the prop, I would say they would be a considerable restriction. I've been running a setup like yours for years with a 502 Mag and I think it sounds great while not being annoying.