Ross Richardson wrote:

The plane came with the conversion. Really makes a C-172 fly. I have the
Bush (aka Avcon or Doyn) conversion. No support from Bush of Udall, KS;
I tried when I needed some information when I purchased the airplane.
Airplains and Penn-Yann also do conversions.

Pluses:
much better climb, somewhat more speed

Minuses:
This airframe does not allow (to what I can find) for a gross weight
increase

you still have 36 usable gallons in the tank and therefore shorter legs
if you push the engine. I usually fly at 60% and try to maintain a 4
hour no reserve burn. I plan for 2.5 hours, though.

Thanks... Sofar we've replaced the wingtips with STOL versions and
its helped with takeoff and climb performance. Haven't cruised with
them yet (just finished it yesterday), but cruise performance before the
change was less than we had hoped for...

They helped the cruise performance of our C152...