for reference...fyi....and fwiw:
I have a 2006, Lowe, twin 25" tubes , 24' pontoon boat. Purchased used.
It came with an '05 Merc 4 stroke, efi, big foot. With just me, on a cool spring day, cold water, I might hit 21 mph.
Currently, I now have a 2021 Merc 115 hp, CT engine, purchased new.
Same...