The latest modification to the AMPhibian: Gates polychain drive belt and sprockets.
I'm not sure if the sound in the video really shows the difference but now the motor brush noise is the dominant sound as opposed to the rattling of the chain and sprockets. The roller chain was already showing some stretch and it's been suggested that #50 chain under changing torque loads and speeds up to 6000 RPM is way beyond it's long term capacity so this should be a worthwhile modification even beyond the noise factor. Also I no longer have chain lube being sprayed around my motor and batteries.
Another possible benefit is I can get two more hubs for the taperlock sprockets which would allow me to swap them fairly easily and double my top speed to almost 40. I don't know if I'll bother since I have no need for that but it might be fun to try and the hubs are fairly cheap.