This would make it quieter:

 

I know if you look around on google and ebay you'll see plenty of small baffles for different mufflers. They're sometimes called db or decibel killers. A quick search immediately had me on another bike forum where someone was trying to accomplish the same thing. I imagine it would just be a matter of getting the measurements correct, and maybe drilling a small hole in the bottom of the outlet for a small screw to hold it in. Some exhausts like Leovince come with them. Obviously your Jardines do not, nor do the old Erions which were basically identical. Again I can't imagine it'd be too hard to find some sort of baffle you could simply fit inside the outlet and into the Jardine baffle and screw it in and it would help you out somewhat. I do know when I bought an old Vulcan with drag pipes on it it was annoyingly loud, and a very small baffle put into each pipe made a very noticeable difference in the volume and sound.

 

Earplugs?

 

Believe it or not an old track trick incase pipes were to loud to get on the track was to put safety wire through the tip, I think it was 2db per piece. I'm not suggesting that just trying to show it doesn't take much to lower it's level.

 

I'm glad you fixed that. I was trying to figure out what "wattsup" wire was, lol. Do you mean to say drill two holes in the end of the muffler, 180 degrees apart, and string a strand of safety wire across?

 

Yeah not sure how this stupid spell correct managed that one, smart phones aren't always so smart! That's the basic concept, you can drill or most would just clamp it but just shows it doesn't take much. Another friend welded a washer to the inside of his tip.