I removed the silent thunder and I'm going to custom fab a new rear swim platform. I threw some rubber external flappers on the stock 4" tips to get me by till the end of the year. I noticed the internal ones were MIA so I ordered a really nice set of aftermarket Dana marine slid in units. To my surprise they are nowhere close to fitting inside the stock tips. The tips are so thick that there's no chance of fitting them in. The Dana ones are lifetime warranty and I like how easy they will be to service if need be. Here's my question, how difficult would it be to swap out the factory tips for some nicer stainless chromed ones? It appears as easy as loosening the hose clamps and remove the external screws holding it to the back of the transom? I'm guessing the stock tips are epoxied on as well? Is it going to be a nightmare to get them off? Second if it's too much trouble I thought about just replacing the original stock ones but it looks as though I'll have to at least remove the internal hose to even get to them so I'm thinking I might as well swap the whole things out if that's the case? Here's a few pics of my boat as well, it's an '89 223SS and also the flappers I want to run.

Do you have a close up of just the rear ?

Sorry those are the best I have for the rear right now. The boat's in storage until the snow melts.

not sure about your model but on the 311's the stock tips are cast Aluminum that have the typical ~4" OD so the 4" rubber hose will fit from the Exhaust Manifolds ....Becasue of the cast Aluminum the tips are thicker than the standard 4" Tip so the ID is not typical id. So you will need to pull the Formula Cast Tips and replace them with typical SS tips .... m