I know they have stopped or at least halted production of these from factory, but are there any distributors or anyone that is still selling them or has them?

2nd part of that, has anyone ever ran them inside of EMI Thunder dry tails? I believe the O.D. of the tail is 4" and that would include the water jacket, so the exhaust tube itself i assume is 3.5" I would really like to try a set of these if I can find them, but I simply cant.

Might have to do that. thx

No go... seems as though they were getting the baffles right from GGB and dont currently have any. He did say they are in process of completely revamping their marine line and will be back in production in time for next season. Michigan only has about a month left boating give or take, might be worth the wait if the tickets don't build too fast!

I have 4" long GGBs in the very short rubber section behind my EMI wet long tails. My risers are 4" OD and somewhere around 3.5 or 3.25 ID. I forget. If you want to put them inside the tails you should find the exact inside diameter of the tails. A machinists snap gauge would do that just fine. The inserts are a hard metal and are impossible to reduce in size. I'd make up a circular disc on a stick and slide it into the tail to be sure there are no obstructions to mess up your installation.
On the plus size they definitely attenuate the exhaust on my engine. They are a reasonable bark reducer that can be undone if needed.
Dry tails never sneak up on anyone!

yeah I plan to do a bit more precise measuring, when the time comes, I dont have the boat at home atm. I assume my dry tails are just an "extended" version of your riser and are the same diameter. I do know from before installing them new they are a straight clean shot, no obstructions.