Batteries are a necessary part of the car. Unfortunately the only time the battery really sees any use is when starting the vehicle.
Because of this there is a lot of room for improvement. Batteries are heavy things, and replacing the stock battery to an aftermarket one could save you as much as 20 pounds!
But lets not stop there. Most vehicles have their battery mounted in the engine bay where there is already an abundance of weight. By relocating your battery to the trunk of your car with a battery relocation kit, you can improve the balance of your car. Every little bit that gets you closer to that 50/50 weight distribution helps!