When I did my little crude test I was using a monster stock. What I didnt think would happen was that the weight measurement was back exactly to where it started no more than a second after hitting the throttle. As far as weight being different. It shouldnt be not if the car is balanced. The only thing that should be different is the more dense mass of the batteries compared to the more spread out mass of the electronics. I dont have a mod to test but it makes considerably more torque so Id assume that the initial torque to the chassis would increase also.