Effect of extra mass on PIDs?

Hi, I recently built a skywalker and am currently in the process of PID tuning. I will add extra load and batteries in the future, but would like to keep weight to a minimum while I tune it, if possible. Will the optimal PIDs remain the same if I add mass but keep the CG in the same spot?

I am pretty sure you would have to fine tune it manually a bit. add weight means adding more inertia. that menas the amount of throttle have to give to accomplish a certain command also changes. do correct me if am wrong.