Hi. when the car has some added mass you need to adjust your setup in order to compensate substeer or oversteer that may occur adjusting the mass position, downforce, suspension, etc. But I'm not pretty sure what to do to compensate the loss in speed and acceleration, particularly with the gear ratios and differential. Any tips will be appreciated. Thanks in advance.

PD: The car I'm using is the FOX

maybe increase the Final Drive ratio VERY slightly to aid acceleration of the increased mass.