Well, to be honest, it's not so much for increasing your acceleration, although it may help a little since the front end will be a bit lighter, but relocating the battery to the back will shift some of that excess weight to the rear of the car, it will definitely change the handling charachteristics, and lessen the understeer problems a little, which is nice while you're driving at speed; an even weight distribution is almost as important as overall weight reduction.
You want to acheive as close to a neutral weight balance as possible (the vehicle's weight is distributed evenly front to back) This is why some enthusiasts love the old corollas so much, it's got a nearly perfect neutral weight distribution.
Besides, relocating the battery will free up space in the engine bay, which is a must when you're trying to shoe-horn engine mods (or an engine swap) under the Hood
. also makes your underhood temps a little lower. The race battery swap idea is cool too, but just remember that it's for racing only. Heck, you could relocate the battery AND swap it for a racing cell for the biggest benifit, weight distribution AND reduction in one shot.
Which reminds me, reducing under Hood
temps goes a long way. wrap your manifolds/headers, increase airflow under the Hood
, make a radiator cool panel, get a colder thermostat. I think it's something like "For every five degrees of temperature reduction under the Hood
, it's good for about 1HP, so, if you reduce underhood temps by 25 degrees or so, you would notice an improvement.