If you are gonna cap y pipes, do both sides of transom assy. Pull exh hose from transom to drive and put a round home depot cap on it. Then tap pipe plug threads into the 2 side exhaust outlets under transom shield. Then if y pipe breaks you dont fail float test...at least as fast. DO NOT under any circumstances do outside plug only. DSPECIALLY if you dont have y pipes and your block off plates have rotted thru. That is how i got my old nova 3 so cheap...

I pulled both of my engines, removed the Y-pipes and installed very heavy duty stainless steel block off plates including new o-rings and silicone sealed around the entire plate. What outside plug are you talking about?

Good point. I never thought of those small side exhaust exits. Instead of tapping how about an expandable pipe plug? Do you know what size tap?

i haven't done it...yet. the boat i bought, the idiot did rubber block-off on 3 inch exh hose and then squirted a buncha caulk up in the holes. instead of replacing the rotted block-off plates. if he trailered it might have survived. but he tied it to the dock and went home. boat failed the float test...i will look at my spare gimball hsng and ck pipe threads at lowes over the weekend. i have enough other stuff to go for anyway...

i dunno if stainless block-offs are a good idea. one more place for diff metals underwater. if one is gonna rot, i would prefer it to be the throw-away plate instead of the outer transom shield it is attached to. especially long island sound.

I looked at my exhaust port from the drive to the housing. Mine is oval so instead of capping it with a rubber hose i was thinking about using spray foam insulation in that port and the other 2 small exhaust ports.I don't keep the boat in the water all the time just a day or so on the weekends. When that foam dries nothing gets through it. If the y-pipe breaks or moves there will be no water inside

I just got 2 of these in the mail today. Super thick and heavy duty. I think they'll outlast the engines even so when it's time to pull engine replace em they're only 100 bucks with new gaskets and shipping at Teague.

those are exactly the ones I used.

For those that have followed or come across this, another option for deleting out your Silent Choice is what I did. and have had no issues in over 13 years.
Unfortunatly like most I did not want the expense of pulling motors, but also was leary about just capping the y-pipe.
So I removed the diverters, disassembled them--removed the internals--and then had the holes welded shut.
Reinstalled the diverter, installed a set of Teague 450's tips, and called it done.
Reasons, MN law does not allow Silent choice, I did not want to fund pulling motors, Most importantly the Silent choice was SLOW actuating! and took to long to close out the 'bark'
I have not had any issues with the y-pipe or the diverter being welded. I am able to run out the thru-hulls as well as some goes down the y-pipe.

I found some black pond and waterfall spray foam that i'm going to seal the 2 side holes and the large exhaust hole. That will keep any water out of the y-pipe.