Decent headunit, good quality door speakers - focal, hertz, rainbow etc. Or Jbl, infinity if your on a very small budget.
And definitely get yourself an amp to run them. Buying upgraded speakers and not amping them is just pointless to be honest.
I'd recommend a good 4 channel amp and run it in tri-mode. 2 channels for your comps, and then last 2 channels to run a decent sub.