Hi Craig,

Please check the bottom of our servo chart on our website:

http://www.futaba-rc.com/servos/futm0029.html

You will not see of course this servo rated at 6 Volts as it is a discontinued item and was not tested out at 6 volts, but rule of thumb for going from 4.8 to 6 volts is that you will gain around 15% more torque and speed over the normal 4.8 rating.

I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.

Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
Also you may want to check our Website at (http://www.futaba-rc.com)