Ive installed one. If all your looking to do is round out your sound they are fine. But DO NOT BUY IT EXPECTING IT TO HIT HARD OR BUMP HARD. It will round out sound but your not going to blow away any one at a stoplight or in a parking lot.
If you do not have a aftermarket head unit you will need a line output converter.
Regardless you will need a amp hook up kit. (power wire, fuse holder, ground wire, RCA's, remote turn on, and speaker wire)