The motor has limited affect on the tweak because the pod weight is placed pretty evenly over the two wheels and the centre pivot. The weight of the pod will come through the chassis dead centre through the pivot, so the effect of the offset motor is on each rear wheel, not the chassis balance. An offset motor will show up dynamically while the car is in motion.
It's more likely that either your weight distribution on the chassis is off - check that by looking at where things are and using some common sense - or that you have an imbalance in the front springs. Other things to check:
That both rear springs are the same length.
That both rear springs seat properly in the car.
That all the tyres are the same diameter.
That you have both ride-height adjusters the same - it's been done!
That both downstops on the front are the same height.
That any additional weight you have added is more to the middle of the car, not to one side.
This tweak method works well and you don't need any other. In reality, if the car turns evenly both ways, and straightens up under power evenly, then what you have before is probably about right.
By making sure the weight distribution on the main chassis is about right and the downstops are set evenly, spring lengths and tyre diameters are the same, I've never had any problem with a Mardave, Schumacher or any other pan car getting the tweak right and having an even turn both ways. HTH
