With the 2020 Toyota Corolla, you have to step up to either the XLE or XSE to get the Premium Audio feature and even then the sound is not all that satisfying for those used to upgraded aftermarket sound systems. Our customer noted a severe lack of bass performance with this SE Nightshade model Corolla and wanted to address this.
We used the Wavtech Link 2 Line Out Converter to get the signal from the factory head unit to the aftermarket amplifier which we installed under the passenger seat. On this car, the front seats are raised up a bit with decent access underneath to run wires and mount a smaller amp. We also hardwired his Thinkware F800 Pro 2-CH Dash Cam.
For a compact sedan like this, 300-500W in the trunk offers plenty of satisfying bass which is exactly what our customer brought us to install. He picked up this setup used which came with a 500W JL Amplifier and 12" ported Atrend box with a 12" Alpine S-Series subwoofer. At the 500W power level, one can expect a decent amount of rattles to start appearing if the vehicle does not have a sound treatment with products like Dynamat or Buzzmat.
Additionally, we installed a set of RSR Down Sus lowering springs on this sedan to give it a sportier appearance. These springs lower about 1.2-1.4" front and 0.8-1.0" rear and still provide a fairly smoooth ride. It's a mild drop that shouldn't attract too much unwanted attention from law enforcement nor make the car difficult to drive on a day-to-day basis.