Ok guys stop bickering! LOL,
On a crappy bow like an Excalibur you should use dissapator bars which the fine Pheonix has. So the next thing you can use but eats fps is tunerz rubber string silencers. If you are any good at serving you can serve on cat whiskers. Make them half the length by folding them over and cuttint the fold and then serve. Do not just tie them in a knot and expect to have them stay on. I use just the bars. Some guys use wooden stocks that apparently really make them quiet. Any thing you put on a string wants to fly off but the closer to the ends of the string the longer they stay but the less effective they are. Just make sure you are close and the deer will never hear the string in time.