One the most common modification you can do to any car is to simply relocate the battery. Despite any popular beliefs that replacing the battery to the trunk does no good performance wise, it actually does. When you relocate the battery you’re simple moving more weight to the rear. On many cars like Evos and WRX STIs or any Front Engine AWD car the front will be slightly heavier than the rear. This is where the battery relocation comes in; by moving the battery to the rear you are basically adding ballast. Adding any form of ballast to increase weight in certain areas is something that is very common in the racing world. It’s done to improve weight distribution to create the 50/50 weight ratio that is KEY to having a good performing car. There also some cons, such as less trunk space, more of a pain to get to if your battery is dead and need a jump start, but these are just minor cons that do not out weigh the pros. So if this is something you are considering to do, I highly recommend it.