my muggy 8s

[Finnster]

What are the temps? Are you getting shut downs?

Getting a 80mm Medusa will not help. Its basically the same motor as a 1521.
You are spinning that motor very very fast. Beyond what is recommended. Lots of power, but lots of heat as a result as well. How many amps are you pulling, and what are the temps of the motor and esc?

Getting a lower kv motor and gearing up may be a better way to go than gearing down that setup.