[Rafi Ahmed]

CIMs do have motor bias, as other motors do. Generally CIMs are pretty well balanced, but it has been known to happen. TBs, as far as I know, shouldn't cause bias "by design". I would check lubrication/assembly of them or motor controller calibration.

There are a lots of ways to control the outputs and make them match each other. "Drive Straight" code is very common for teams to use.