bigbulls i make my own strings i would go with 452x by bcy 35% vectron 65% dyneema vectron for no strech dyneema for speed best of both worlds. ultra cam is about 55% vectron and 45%dyneema a little heavier but will not strech might be pron to breaking but have not broke one yet as for as pure dyneema or ts1 they will strech even if there prestrech thats the nature of dyneema. bcy puts just enough vectron in to make it not strech and not be brittle real good speed because of the dyneema .try some it made me happy. i just bought a pro 40 with ts1 or dyneema and it was stech 1 1/4 inches and thats with a new bow with prestrech and all string if you want to get a string that stays get some with vectron in it.bcy 452x is your baby