Regardless of what is used the results won't be much better than stock, and that's not saying much because there's nothing worse than stock. Granted the new system is better than the older units, but still sub-par compared to entry-level aftermarket equipment.
You won't see any significant improvement until you move into an amp and speaker setup with a line leveler to modify the signal coming from the HU. The HU is the weak link and it puts out a crap signal to crap speakers. Adding better speakers will just give you a (slightly) louder crappy sound. To really get it cranking and increase the sound quality requires an amp and line leveler to flatten out the signal from the HU so the amp/speakers can do their job better - I say better because no line leveler (or flash for that matter) with totally fix the signal from the HU.
Freedom isn't free, remember to thank a vet.
2018 CVO RG lava orange, 117 Stage 3, 14" F47 and a few chrome extras. Boom crap gone.
2016 RG Special Cosmic Blue, 120ST with Dragos 2:1 and TTS tuner, FBI drop seat kit and JNR air ride. Stock audio long gone.