I shot the Carbonwood 3000's for a few years before switching to the Beman MFX shaft but what I found is the 3000 spine was in between the GT 55/75 and 35/55, slightly weaker then a 55/75 and just a little stiffer then a 35/55 almost like right in between those 2. I bareshaft all my arrows and could shoot the 3000's at 29in with a 100gr insert and 125gr tip. With a GT 55/75 I had to shoot them at least 30-31in with same tip weight and the 35/55 at 28in were too weak for my bow. My spine tested shows the same difference as well.