Here's a pic of Flemish dacron, which I call dog chokers. they stretch forever and don't shoot any faster than endless loop dacron or Excel. Not sure if these are available anymore, but sacve your money.

Actually, the absolute best strings I've ever tried are Boo's aka Dnk. Servings last forever and they all seem to shoot same fps.

If you shoot an Emax, you'll get about double the serving life w/ our buddies creations, lol. Works of art to boot!