I don't know if this apply's to anyone else but personally there are only 3 reason's I add weight to a car...
1 - Add weight at either end to change the weight distribution and balance of the car.
2 - To keep the front end of a 2wd down.
3 - To get up to the weight limit (
)
I always prefer my cars to be lighter and need less motor for adequate straight line performance, making them like a brick and then going for the brute force method of adding more power seems a bit silly to me. It takes more effort to get the thing moving and change direction, all the electrics get hotter, tyre wear (and wear and tear in general) is worse. A lighter car will recover from bumps more quickly too as there's less weight to stop moving, also in my experience a lighter car is no less stable through bumps
if your shocks are right...
When I was running the B4 the only weight I had in it was the Trish front bulkhead (40g) to keep the front on the ground, move the weight forward a bit and get up to the weight limit. And the squat block (28g), to get up the the limit and balance the bulkhead which moved the weight a little too far forward, it was under 1500g...