I’ve been asked to add an extension to this shaft and would like to know how much and where it would affect the profile
A 1/2″ extension will not affect the bend profile of the shaft, as long as nothing is done to the head weight. For instance, if you extended the club and then wanted to remove head weight to maintain a swingweight at the extended length, the shaft would play and feel a little stiffer. If you do nothing to the headweight and just let the swingweight go up with the additional length, there should be not noticeable difference in the flex profile.
Britt Lindsey