I have maybe $85 into my stereo in the SD as of the current date (bigger fish to fry before doing anything else there) and it's amazing how poor the OE system is by today's standards. The SDLs sounds far and away better than the SDs.
The HU I have is an older Pioneer Premier (no dancing dolphins
) and some junkyard score Blaupunkt speakers. I paid I think $6/ea speaker, it was a killer deal and I found them getting some old 7 series BMW parts. The travesty!
But I'm very pleased with the sound from those speakers, much greater than I assumed they'd have provided. New speakers make a world of difference and used ones are great deals online... Polks older EX and DX line sound great and can be scooped up for next to nothing.
As for remote controls, they're great in a car. They allow you to keep your eyes fixed on the road without having to look down to change the source/station/volume. It's very nice once you're used to it.