This 2017 Subaru WRX STI got in contact with us after deciding to move his equipment from his 2010 Mitsubishi Lancer Evo X.
This installation came with its own set of challenges since the STI was equipped with the factory Harmon Kardon system. This meant the signal for the door speakers was bandpass limited and not usable for a subwoofer signal! In the end, we used a summing device to combine the signals from the factory subwoofer with the rear doors!