**Update** 9/7/17 The GSI strings seemed to get a bit like harder tension strings so I went back to DÁddarío EXP45 strings.
I have always liked GSI and their strings. I wanted to try their Super Treble Medium Tension strings on my Andy Culpepper # 83 Flamenco Spuce top Blanca. They sound and feel great, intonation is perfect. I ordered a bunch today. For me the high Tension strings like those in D’Addario EJ46 & EXP46 were to hard on my left hand and stiffened the tops flexing and overall tone. My string scale length on this guitar is 658mm. What GSP says on their web page “Our own custom made classical guitar strings, are wound on a very unique multifilament nylon core. We were the first to market our unique nylon Super and Ultra Trebles – now used by several of the major brand string makers. We now have Super and Ultra Hybrid Trebles – a little brighter and more powerful than the Supers and Ultras. Quality of sound and production, and consistency are what guitarists have come to expect from GSP Strings.” GSP Webpage
Nylon Live 