In a word, no. I shoot Excals, have had some of the stick on limb type, cost a lot of fps, and they don't work that well and eventually come off. The string toys you put between the strands don't last more than a few shots and don't make much diff to begin w/ The life expectancy exception is served cat whisker which I get on my Boo strings.

Imho, the cheapest and best xbow silencers are heavier arrows. The rule of thumb is 1 fps for every 5 gr change in weight. Say you drop 20 fps w/ limb and string fluff. You could go up in arrow weight almost 100 gr, have better k.e. and nothing to go south on you.

Just my opinion.