I bought a pair of highly-recommended Kohler 1.6 gpf toilets. Both are
the first 1.6gpf toilets I've owned.

After a few months of use, I've found that basically, both of them are
great unless someone does more than urinate in the toilet. If they do,
the toilet requires pretty much two flushes. The problem is that it's
usually the next person coming along that finds this out and has to do
the flushing.

Obviously we'd like to address that. I opened up both toilets hoping
to just extend the left float device to allow more water into the tank
but find that both toilets have center assemblies (sorry, I don't know
the proper terms here) where the overflow goes that extend right up to
the lip of the water. Thus if I raised the float device, the extra
water would just flow into the center drain tube forever.

What is everyone doing to deal with this? Is there an extension for
the center assembly? Is there a better way?