[Cody Carey]

It all depends on what kind of wheels you are using... The KOP gearboxes with two CIM's output about 175 foot lbs of pushing power, and unless you have very grippy wheels, that is not your bottleneck. Like Luke said, the KOP skyways won't do much in the way of traction, no matter what kind of torque is put into them, they will just spin the second you get into a pushing match. I would try getting more traction with your wheels before adding the two motors, you can do this with zip-ties, or some IFI tread, or a little belting screwed to them in place of tread, aswell as any number of other ways.

*EDIT* I don't think that adding another CIM to only one side of your robot would make it lopsided, as it would only cause a difference in torque, not speed. It might even be your best bet, once you have ample traction. At pittsburgh, we were able to play a KILLER defense with only one side of our drive train, and we use 2 CIMS in each gearbox, one gearbox to a side. By killer defense, I mean that we were still able to push everybody that we tried to, even having only one functioning gearbox. *EDIT*

Hope this helped,
-CodyC