If you do nothing to the head weight, the actual flex stays the same. The frequency number changes, but that just moves the dot on the graph to another point on the same flex line. As Rlafoone stated, if you reduce the head weight after adding the length in an attempt to lower the swing weight, the shaft will play stiffer. That being said, lengthening the shaft 1″ and doing nothing to the head weight may not change the actual flex, but the club will feel different than it did at the shorter length. Obviously it should feel heavier. How the flex feels is totally random. I have had some say they feel more flexible and others say they feel stiffer. The important thing is to get the length fit correct and then evaluate the performance from a ball striking and ball flight standpoint to see if it is what you want.