@Robbyg With respect to your question regarding gyro sensor drift here:
With the configuration of your wheels, the gyro sensor does not appear to be in the center of rotation. In this case you are not “off” because of drift, but because you are progressing through and arc with the sensor instead of spinning “around” it. Try moving your sensor to the center if rotation and keep it away from wheels and the brain as best as you can.
That makes no difference. Try it for yourself on a properly working gyro. Translation happens all the time by driving your robot around and moving the gyro in an arc is just a slightly different case of translation superimposed on the measured rotation. Vibrational noise does affect the gyro precision, so your advice is sound in general, but @Robbyg has issue with a consistent 30% error even for careful manual turn, not a little drift.
It’s funny because someone else told me the same thing today about the translation, but I can’t reconcile it yet.
Maybe his location to the motors is an issue. EMI can affect them as well.