Depending on when they were bought and manufactured.
Kohler, AS people would admit that original low flow
designs were pretty bad. They did not have a lab, and no
testing was performed.
Now they saying gov should lower to limit to 1Gal,
On the new house we have all low water use 1.7gpfs,
and they work much better than 3.5 we had on the old
Don't buy $49 models like Menards they don't work.
Bush toilet models just make sounds like:
mmmm, a-a-a, NUKULER and put you in the deep debt.