[dlsmith]

A couple of other thoughts on this, in addition to the calibration suggestion which is the place to start.

Talons and Victors have "brake/coast" jumper selections, so if yours also have something like that you should make sure they are both set to the same setting.

Also, we found that Victor controllers don't have quite the same speed curve if you drive one side with reversed polarity, i.e. SetInvertedMotor() or something like that. For most drive systems the motors are oriented in the opposite direction (left/right) on the robot so one side must be inverted. You could try swapping wiring polarity on one side and invert in software so both controllers output the same polarity, and see if the speeds match up better.

If mechanical friction is mismatched, then about all you can do is compensate somehow using either encoders or maybe a gyro to keep the robot moving straight.