You can do it yourself. Be mindful of mounting depth, type of speakers, etc. In my previous car I had 3-way kicker speakers in the front and NAXA NCS-769 6-Way speakers in the back. It sounded like I had a subwoofer inside the car without an actual subwoofer. The NAXA speakers are cheap but lasted like 2 years of daily commuter/weekend house music bumps. It also matters on the how you set up the sound as well as the quality of the music itself.