A GAI of 165 is different from older IQ scores in a few ways. For one, it is indeed based on different scoring norms; though extended scoring can boost a number on the SB5 or WISC-IV a bit, whether FSIQ or GAI, a score of 165 today is much more rare than a 165 on older tests, particularly the SB-LM. It's also measuring different things, or at least in different combination. There are tables of rough estimates of giftedness levels based on scores obtained from either the "old way" or the "new way", and I'm positive that an IQ score or GAI of 165 falls comfortably within at the very least "extremely gifted" territory today.
