A good unfiltered and no bass roll off solution would be this:
Amplifier Integration Interface for Select 2014+ Toyota and Lexus vehicles with Premium Amplified Sound Systems - PAC
JBL amp has internal processor with crossovers and bass roll off when you turn the volume up.
Cheap option would grab front door speaker wire as it goes into the passenger front door boot.
Twisted pair
front right pos Lt green
front right negative blue