I went through this with all variations of lighter and heavier shorties and I made different battery bars that would position them at various spots forward or rearward. I did this while trying to balance out the car perfectly on the scales depending on the shorty weight. The car drove well but then the one race I had forgotten to actually hit start to charge my battery so I threw in my full size Protek battery which made the car heavier and unbalanced on the scales but it drove so much better and that final came down to just a nose that night. I've kept racing with the full size pack ever since because it just feels better to drive. So I say if you have different batteries experiment and see how the car feels to you when driving when your tires are in a similar state.