[dosland]

They're often just called carbon strings, and on a guitar they don't travel quite the same linear distance as on a fishing rig. Also, the main points of contact are the nut (hard plastic or bone), the saddle (hard plastic or bone), and the bridge (probably some very dense wood). The only caution I have with the carbon strings is they're a bit thinner, so an extra loop at the bridge or a slightly melted end or even some "beads" might be helpful in preventing slippage. They're definitely worth a try, I think there's a more audible difference from "nylon" to "carbon" than across all the different types of traditional string. Your ear and guitar will have to decide if that difference is good.