Its JL so you know it will be pretty decent. Cracks me up that it is rated at .25ohm and has a .25 ohm voice coil. maybe so the amps rails can run at 12v instead of having a step up power supply./
It wont degrade the other speakers the input impedence will be very high to the speaker level inputs. The last time I installed a car stereo, the late 90s, you had to be careful with bose wiring because the speakers were built as modules with electronics and amplifiers local. Not sure if that is still a thing, but you need access to the speaker level analog signal.
I think 12 in jl may be overkill for a factory system. Would be tempted to try to sneak something like this under the seat, if there is room.
https://www.crutchfield.com/p_109BASPRO2/JBL-BassPro-SL-2.html?tp=114