We stock 6.5" subwoofers that will provide your car audio system with that extra punch you're looking for.  A 6.5" subwoofer can mount in a huge variety of spaces due to its small size.  You can even mount these 6.5" subs in your door, or next to much larger subwoofers in your trunk.  The possibilities are endless, these component subwoofers will allow you to add bass right where you need it.