I did a lot of the fly off time for Dave Johnson when he was
developing his original STC for the first 180hp Cubs.
The climb performance over a stock 150hp Cub was amazing. With the
150hp Cubs, we could not tow
the 2-32's out of the Black Forest Gliderport (elevation 7200') when
the temperature got much over 70ºF.
With the 180hp, there really was no limitation on glider weights or
density altitude for our ops requirements.
We even towed a few gliders out of Leadville (10,000') several times,
and flew fully loaded 2-32's out of
Aspen, Gunnison, Durango, and several other high altitude airports
without problems during Dave's annual glider
caravans around the state of Colorado. That was something we couldn't
do with the 150 Cub.

One particularly rememberable tow was into the wave near Pikes Peak,
when the wave wasn't really working.
For whatever reason, the 2-32 pilot wouldn't release, and the tow was
continued until I waved him off at
18,000' (Old days, Positive Control Airspace began at FL240 then).

Steve
PS