Guitar string is what we always used to remove windshields back in the day. You pull it back and forth to "saw" through the sealant. Even though you might hit the studs, you may be able o get enough of it off to minimize gelcoat damage. Maybe use this method combined with a few of the others to get them off.

Are you sure they used 5200? That is generally something you use for a permanent installation, like a swim platform that is below the waterline. 4200 or just regular marine silicone is usually fine for thru hull tips. Also, if Formula didn't already do it for you, now would be a good time to get some resin and glass in the openings where the tips pass through the transom. That way, if you ever do develop a leak hear, the water will pass relatively harmlessly into the bilge instead of wicking into the core of your transom and rotting it out.

On the 5200 or 4200. Jeff from MTC called Formula factory and for a span of a few years they used 5200 on the mufflers, early to mid 2000's and my boat falls into early 2005 assembly. They have stopped using the 5200 on the mufflers just for the fact of removal, that's a no brainer. Now we have to get a solution to their bad choice, not the end of the world just trying to get this done without damaging the boat. Thanks for your suggestions.

Try this also http://www.marineformula.com/

Never used it, but heard it works well.

I think I hit the center rod or bolt with the die grinder when I was in there... It was pretty rusty and came apart fast..... I had lots of rust inside and wanted to get rid of everything inside as it was in bad shape..... TBF

Great, I will pass this on to the tech

Rust Inside? Thought these were full stainless steel? For the $ they should be!

I bought my boat with no engine and the exhaust was still in the boat attached to the corsa system..... Obviously the stock 502 exhaust was gone but I was surprised to see rust in the diverters and tips.... I had to replace the diverted valves as there was not much left of them and it seems the pieces that broke off sat for years and caused the rust. But with some work and new parts it all cleaned up well! Salt water is nasty and I am a big believer in using salt away after every use..........

Also, stainless steel is not rust proof but more like rust resistant....I have seen plenty of stainless parts rust but it does take a lot longer......

I am planning to gut my silencer tips on a 28ZX tomorrow with a plasma cutter. I have one tip off and want to see how it does in the shop. I am hoping to do the other 3 while on the boat. Anyone have any experience with this??

Don't do it!!!
You can buy nice non-baffle tips for what you can sell your current ones for. The screw you see in the middle is not holding the structure in. The structure / baffles are welded to the shell. I did it once and will never do it again!