Car over heats when I have my system on

The power draw may be slowing down the cooling fans. You may need to install more batteries and a heavy duty alternator. In a couple of years you won't be able to hear anything so the problem will take care of its self.

Agree. It sounds like you are overloading your electrical system with the current draw required to power your subs. You are also probably seeing your headlights diminishing in intensity. You will need to boost the system as FOR indicated to get the sound you want and a car that can handle the load. If you don't you will stand a good chance of starting a fire or blowing a major fuse.