My pitch originally was 130 Hz - my everyday voice was more like 160 Hz though - but sometimes I dropped. Now its usually around 180 Hz, sometimes 170 - if I am in a good mood it almost goes to 200. That is an increase of officially about 40 Hz I guess, but I am not sure. I know that pre OP I never managed to really release my voice anymore to pre transition levels. I suspect it may actually have been 110 Hz instead. So that would make the change more like the 60-70 Hz that is assumed for this surgery. On the other hand, I can still use a 130 Hz voice if I really want to now, but it sounds a bit fake and broken.
I think the surgery mostly switches the sweet spot where our voices are willing to behave properly and sound good and comfortable. Involuntary sounds are higher, relaxed humming is higher - the base pitch is higher - and the low pitches are sounding more broken and false, so part of the process for me was to actually intentionally use higher pitches because I consciously knew they work better while my subconscious tried to pull the pitch down out of the old fear of overstraining my voice, which I did a lot pre OP just by using a pitch above 160 Hz, which now is the norm for me. So my brain has to relearn that now "relaxed" is where previously "strained" was... Tell that to the brain - I think it would have believed me much more easily if I was still 15 years younger 😀