I am planning to upgrade my Lexus IS 350 Mark Levinson system with a used JL 12" Subwoofer with a customized enclosure. I only planned to replace the subwoofer and not the internal speakers.. I know I need to add a AMP what do I need JL 500/1? and Cleansweep? I am new to car audio system.

I am also concern about the balance of the audio.. Mark Levinson designed the subwoofer to be balanced with the sound with the other speakers in the car.

Anyone done similar upgrade? What would you recommend I do?