with 205/45/16 you have a sidewall height of 92.2mm. 205/40/17 gives a sidewall of 82.0mm. So that gives a total of 20.4mm of tyre height you are losing by going to 17s from 16s. 2cm - can that really make such a difference?
It makes me wonder what going from from tyre size of 195/55/15 to 205/45/16 would feel like, as that would be 3cm less?