I think part of your issue is using the carbon fiber pieces instead of the shocks. Think of a chair with 4 legs and 1 leg being slightly shorter. It will stand on the 3 legs, and exert less force on the 4th (to the point of possibly no force if the leg is short enough). It could also be chassis tweak or the level of the scales as mentioned as well.
I'd put the shocks back on it and reweigh to see if the results are repeated.