Not necessarily so. There are other options.
First, hold the handle down. The 1.6 gallon flush is based
on the flapper automatically closing with a flush.
C'mon, measure the amount of water in the tank, and do
the math. I just measured the inside of a 1.6 gallon toilet's tank.
17 inches across, 8 inches front to rear, and 9 inches from
the flapper valve to the top of the overflow. 1224 cubic inches.
That's 1224/231= 5.298 gallons.

And there are ways of having even more flush volume without
going to Canada. Main is with an adapter that adapts the bolt
pattern of an old tank to the spacing of a new commode. That
adapter is about $5.


Rudy wrote in message
news:_hAYc.267866$gE.108643@pd7tw3no...
Kohler Highline (a tall Wellworth model) is 16.5" high VS about 14" for
normal toilets.
Theyre ~ $ 147.50 at Lowes and HD in the USA. To get the 5 gal, you'd
have
to find a used older model
which would prove tuff to do, or get one in Canada where they still sell
them.

R