I got fed up with my peep today and took off the rubber that pulls it in line. Intantly I could tell my bow was much much quieter and by the sound of the arrow flight I gained speed. Havent checked it yet on a chrono. Tomorrow I'm taking it in to remove the peep totaly. It is a very liberating feeling to shoot without being confined to a peep sight.
As for sound, the string leaches will do a better job than wiskers and wont slow your string down as much. Also if your picky about it like I am I'd add a set of limb savers they work great. Since I'm shooting a bowtech I slid the vibrablocks all the way down and added the limb savers also and my bow got virtually silent. I'm not sure about matthews though.