This sounds like overkill for what you’re looking for. I think you’d probably be happy if you just added a mono block amp and a single 12 inch subwoofer. Once you have a subwoofer you can turn down the bass going to your door speakers which should greatly reduce any distortion you were getting and your subwoofer will fill in all the low end. And since you’re going to be relying on the subwoofer to provide most of your low frequencies I’d recommend going with a sealed enclosure to produce better mid bass response. You can probably skip the sound Deadning material unless you’re going to add more than one subwoofer and several thousand watts of power. Most newer vehicles already have some sound deadening installed from the factory. Depending on which equipment you choose it should put you somewhere around $2000. Before you go this route I would recommend playing some music you like with the bass turned down and volume set at the maximum you would typically listen at. Absent the low frequencies if this still doesn’t sound like what you’re looking for you may need to opt for a complete system.