I have the Eddie Marine Double X Slip-in Silencers, and run them on occasion. Depends on the place I am going, and the event.
The ones from EM are shorter than the ones from Teague. This is important because they have to be completely inside of your tip, AND not impede the movement of your internal flappers.
Call Eddie Marine, and get on overall length measurement of the piece, and then stick a tape measure in your tip and make sure the short edge of your angled tips has enough length from your internal flapper so everything fits enclosed. I did have to remove my tips to install them, as you have to drill a hole in the very bottom center of each tip for mounting. They were also a hair bigger than 4" so I had to grind them down a bit.
I lose 100-200 rpm with them installed depending on the heat of the day and the load/fuel I am carrying. Its nothing noticeable for the most part. The sound is definitely toned down when I have them installed; but I don't have a db reading either way.