Upgrade my old LTKR120 for motor and flight controller.
I use 1304 4000KV mortor and 2 inch 5 blade props. It's almost silent for 3S 850mah, but uses 50% throttle for hover.
If choosing 3 inch prop, battery can use 4S 18650 3500mah for flying long range or use 4S 1000mah for racing.

Update:
The prop noise
3" > 2" > 2.5"
So current 2.5" prop is the most quiet and uses 38% throttle for hover(3S 850mah).

Update:
Upgrade to bigger 19mm camera, so the frame need to increase height to 20mm
Therefore, the props need to decrease to 2.4"