This past weekend Kevin brought his spine tester he made with all the up-grades to the range. He was giving a demo and we decided to check my goldtips (55-75) they rate these at .400 spine. first we checked with cock feather up...330, next hen feather up .365 next hen feather up .390 now some 70-75 woods all 3 perfect 73# last shaft tested. was a easton carbon rated at .400 spine. checked with each feather in the top spot. all right on .400...... My son an I noticed that the Easton Axis just flew and grouped better. we checked the spine of the other GoldTips and found the same results. also found the the Trad Goldtip 55-75 spined alot weaker than the black 55-75 GT. Both were the XT model..............