The HPWC can provide up to 48A so you might have required a 60A breaker anyway depending on code. I guess that varies depending on where you live.
Supercharging does not use that amperage setting... but supercharging on an RWD does have a lower max amps (thus kW) it can accept. Previous SR+ were limited to 170kW (instead of 250kW for AWD/Performance) but the latest RWD might go a bit higher... I don'T have the exact number but it's in that ballpark.