I know you can't change the size of the pulley on the molded spur gears, but it would be interesting to change the amount of teeth on it. After watching an XRAY with a special gear set fly past me, I considered it. What do you think?
To lower the internal gear-ratio, you could try to put in two of the 41T diff pulleys instead of the std. 42T. I don`t know what the ratio would be though, does anyone know(the nr. of teeth on the spur-pulley)?