i have a 1991 civic si and a 1991 civic both hatch one has the 4 speed and the other has a 5 speed both cars run and drive fine but i want to know if you can put a ring gear on a 5 speed out of the tranny or is it not worth it i am about gas milege but still want to get up and go would this make my gears taller or not and would it work?