Thinking about getting a meanV CSS. Almost all the reviews have been good, but I have one question. How can it increase bow speed? All it does is stop the string, right?

I don't know the physics but it does. I would guess that is has something to do w/ cutting the string oscillation down.
The MeanV I added gave me 5fps. additional.

It may also quiet the string enough to remove any other leeches, jacks, whiskers etc. that you have on the bow.

I can't prove it but I would think that once the string passes it's original position, it would start slowing down.

That's when the arrow would be released. At least is makes sense to me.

The theory is that it allows for a "cleaner" release, as the string is stopped abruptly as it reaches brace. If you've ever watched slo-mo videography of an arrow being shot, the string goes way beyond brace, and sort of "holds on" to the arrow, or more appropriately, the arrow holds onto the string. Some people think the string "pulls" at the nock as it swings back the other way -- VERY minutely, of course -- but enough to cause a 2-5 fps speed loss on the arrow.

Those explanations make sense. Unfortunately, I looked at my Element and realized that the riser is not tapped to receive a CSS. Guess I'll have to wait until my next bow.

Some CSS and STS are available with a front mount so that you can attach it where you stablizer is and then screw your stablizer into it's mount.

STS is making a side mount system this year. I'm not sure if they are available yet. I positive they are going to fit Hoyt risers, but I 'm not sure what other models. They probably are riser specific.

String silencers like leeches and whiskers slow an arrow down several feet per second and with the CSS guys are removing these string silencers and this is another way people claim to pick up speed.