Audio Systems: Car Audio Help

Question
I have installed sony xav-65 with component speaker polk audio db6501 in front and jbl cs-6c in back.i am still not happy with them. This was the best reasonable combination as i was told, i want to add woofer what will be best possible woofer and amplifier for this combination.
i have hyundai i20 car

Answer
So you don't have a technical issue or problem,  just not happy with your brands? Maybe I don't understand

I don't do brands, all I can tell you is that you have a very bad combination of equipment

Radio its only 17watts per channel with distortion  speakers hold 200w  and needs 50w rms to move

Yes, you can add a woofer to a Hyundai, or any vehicle but you have other problems to solve first