Have a full Bodied Yamaha Acoustic that had Elixir polyweb light. That all but destroyed the performance! Went to these and i am absolutely amazed at the difference strings can make. I know they can, but, holy S**T !! What an upgrade. Forget "Poly". It's "Nano" from now on as well as 80/20 Bronze! It's as if i bought a new guitar and a far more $ one at that. Low -E to High- E , all strings resonate brighter, longer, truer. Albeit I now know that a full body needs a heavier string, the sacrifice is the increased force to fret the strings. Just have to toughen up, strengthen my left fingers. Feel, playability is smooth. I feel I made two changes at once but both in the Right Direction.