If you like you spend a lot of time in your car and even if you don’t it may be the right time for an upgraded car stereo system.
If you have the funds available or are looking for a new project why not consider purchasing upgrading your head unit, sub and amp. You may even consider making the MDF for your Subwoofer enclosure yourself so you can customise to your own specifications. That way you can look to feel every low end frequency as it was intended to be heard.
With your subwoofer customised you may even be able to look at getting your multi-channel amp configured so reduce any power surges. Amps will allow the other range of frequencies to be processed correctly too.
Compatibility is crucial when putting a system together. The Sub, Amp and head unit need to be in perfect unison. In terms of configuration of sound and overall listening or viewing experiencing (if you install a console or DVD player in the car) it is down to personal preference but its a worth while project.