jm2c, ymmv… but the best thing you can do for any of these cars if you really want some sound is a decent subwoofer. The “why" is just physics - your response rolls off as the wavelength of the sound exceeds the diameter of the driver. 5-1/4” works out to about 2.5kHz at sea level. It’s why you see ports, big cone excursions and lots of wattage getting thrown around.. to overcome the tiny drivers and their terrible impedance match with the atmosphere. In fairness, low C on an organ is ~16Hz which is... 32 feet. Not exactly practical..
If you cross-over the little guys in the doors at 1k, or even 500Hz they will be much happier and you won't waste power trying to do sisyphean things with your car audio. Besides, lows are omnidirectional so it barely matters where you stick the sub. Have fun whichever way you go!