my old work car, a 2009 holden combo, the standard headunit in that wasnt bad, mind you, blaupunkt stuff is pretty damn good...
i had reference series 6.5in fronts with active crossovers and tweaters, and reference series 6x9s 3 way, when hooked up to the headunit they were kinda naff, once you amp those infinitys... wow they love it. used cheepo crappy subs as back in my youth i was only after volume, had a 1200w sony 2way amp and 2x sony subs.... good for getting noise control notices from 3 blocks away and for recieving a fine for broadcasting...
taste has refined somewhat, searching for a reasonable sound for cheep.