It's a buffer, It's a good thing to help keep power stable. It is more important to make sure you have adequate wiring, do that first.
My friend has a decent cap in his system, and we simply hooked it up to a distributor block, as if it was an amp. It may not be the most efficiant use of it, but it was an easy, clean install and it helps. Don't forget to use the small resistor to juice it up for the first time or you'll scare the bejezus out of yourself (and probably wreck lots of electrical components too)