FL160 is totally unrealistic in a C172. Even FL80 is very high. Your ears would hurt like hell, you’d feel very light headed and possibly even pass out. I’m talking about a scenario when you take off from sea level. I have never flown that high in an unpredsureized cockpit, but I have clibmed 10000 ft mountains and remember feeling much weaker. And that was after a full day climb, so you could get used to it.
I fly the C172 regularly and 99% of the time it’s 2000-3000ft.