Powering a Car TV, amplifiers, and woofers

What mods must be made in a car in order for a TV in the headrests, amplifier, and woofers. It might get some neon underbody kit too. Basically, my question is what do I need to install in my car in order to have enough power for all these electronics. Id rather have too much power than not enough or just enough. Thanks!

Unless your going to be pushing some powerful amps (witch it sounds like your not, or you would know the answer to this question) then your not going to need to upgrade anything.

if you need anything, maybe a high output alternator.